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| author | Jacob McDonnell <jacob@jacobmcdonnell.com> | 2026-04-25 19:55:15 -0400 |
|---|---|---|
| committer | Jacob McDonnell <jacob@jacobmcdonnell.com> | 2026-04-25 19:55:15 -0400 |
| commit | 253e67c8b3a72b3a4757fdbc5845297628db0a4a (patch) | |
| tree | adf53b66087aa30dfbf8bf391a1dadb044c3bf4d /static/netbsd/man9/uvm.9 3.html | |
| parent | a9157ce950dfe2fc30795d43b9d79b9d1bffc48b (diff) | |
docs: Added All NetBSD Manuals
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diff --git a/static/netbsd/man9/uvm.9 3.html b/static/netbsd/man9/uvm.9 3.html new file mode 100644 index 00000000..19108045 --- /dev/null +++ b/static/netbsd/man9/uvm.9 3.html @@ -0,0 +1,580 @@ +<table class="head"> + <tr> + <td class="head-ltitle">UVM(9)</td> + <td class="head-vol">Kernel Developer's Manual</td> + <td class="head-rtitle">UVM(9)</td> + </tr> +</table> +<div class="manual-text"> +<section class="Sh"> +<h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1> +<p class="Pp"><code class="Nm">uvm</code> — <span class="Nd">virtual + memory system external interface</span></p> +</section> +<section class="Sh"> +<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1> +<p class="Pp"><code class="In">#include + <<a class="In">sys/param.h</a>></code> + <br/> + <code class="In">#include <<a class="In">uvm/uvm.h</a>></code></p> +</section> +<section class="Sh"> +<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1> +<p class="Pp">The UVM virtual memory system manages access to the computer's + memory resources. User processes and the kernel access these resources + through UVM's external interface. UVM's external interface includes + functions that:</p> +<p class="Pp"></p> +<ul class="Bl-dash Bl-compact"> + <li>initialize UVM sub-systems</li> + <li>manage virtual address spaces</li> + <li>resolve page faults</li> + <li>memory map files and devices</li> + <li>perform uio-based I/O to virtual memory</li> + <li>allocate and free kernel virtual memory</li> + <li>allocate and free physical memory</li> +</ul> +<p class="Pp">In addition to exporting these services, UVM has two kernel-level + processes: pagedaemon and swapper. The pagedaemon process sleeps until + physical memory becomes scarce. When that happens, pagedaemon is awoken. It + scans physical memory, paging out and freeing memory that has not been + recently used. The swapper process swaps in runnable processes that are + currently swapped out, if there is room.</p> +<p class="Pp">There are also several miscellaneous functions.</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="INITIALIZATION"><a class="permalink" href="#INITIALIZATION">INITIALIZATION</a></h1> +<dl class="Bl-ohang"> + <dt id="uvm_init"><var class="Ft">void</var></dt> + <dd><a class="permalink" href="#uvm_init"><code class="Fn">uvm_init</code></a>(<var class="Fa">void</var>);</dd> + <dt><var class="Ft">void</var></dt> + <dd><code class="Fn">uvm_init_limits</code>(<var class="Fa">struct lwp + *l</var>);</dd> + <dt><var class="Ft">void</var></dt> + <dd><code class="Fn">uvm_setpagesize</code>(<var class="Fa">void</var>);</dd> + <dt><var class="Ft">void</var></dt> + <dd><code class="Fn">uvm_swap_init</code>(<var class="Fa">void</var>);</dd> +</dl> +<p class="Pp" id="uvm_init~2"><a class="permalink" href="#uvm_init~2"><code class="Fn">uvm_init</code></a>() + sets up the UVM system at system boot time, after the console has been + setup. It initializes global state, the page, map, kernel virtual memory + state, machine-dependent physical map, kernel memory allocator, pager and + anonymous memory sub-systems, and then enables paging of kernel objects.</p> +<p class="Pp" id="uvm_init_limits"><a class="permalink" href="#uvm_init_limits"><code class="Fn">uvm_init_limits</code></a>() + initializes process limits for the named process. This is for use by the + system startup for process zero, before any other processes are created.</p> +<p class="Pp" id="uvm_md_init"><a class="permalink" href="#uvm_md_init"><code class="Fn">uvm_md_init</code></a>() + does early boot initialization. This currently includes: + <a class="permalink" href="#uvm_setpagesize"><code class="Fn" id="uvm_setpagesize">uvm_setpagesize</code></a>() + which initializes the uvmexp members pagesize (if not already done by + machine-dependent code), pageshift and pagemask. + <a class="permalink" href="#uvm_physseg_init"><code class="Fn" id="uvm_physseg_init">uvm_physseg_init</code></a>() + which initialises the <a class="Xr">uvm_hotplug(9)</a> subsystem. It should + be called by machine-dependent code early in the + <a class="permalink" href="#pmap_init"><code class="Fn" id="pmap_init">pmap_init</code></a>() + call (see <a class="Xr">pmap(9)</a>).</p> +<p class="Pp" id="uvm_swap_init"><a class="permalink" href="#uvm_swap_init"><code class="Fn">uvm_swap_init</code></a>() + initializes the swap sub-system.</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="VIRTUAL_ADDRESS_SPACE_MANAGEMENT"><a class="permalink" href="#VIRTUAL_ADDRESS_SPACE_MANAGEMENT">VIRTUAL + ADDRESS SPACE MANAGEMENT</a></h1> +<p class="Pp">See <a class="Xr">uvm_map(9)</a>.</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="PAGE_FAULT_HANDLING"><a class="permalink" href="#PAGE_FAULT_HANDLING">PAGE + FAULT HANDLING</a></h1> +<dl class="Bl-ohang"> + <dt><var class="Ft">int</var></dt> + <dd><code class="Fn">uvm_fault</code>(<var class="Fa">struct vm_map + *orig_map</var>, <var class="Fa">vaddr_t vaddr</var>, + <var class="Fa">vm_prot_t access_type</var>);</dd> +</dl> +<p class="Pp" id="uvm_fault"><a class="permalink" href="#uvm_fault"><code class="Fn">uvm_fault</code></a>() + is the main entry point for faults. It takes <var class="Fa">orig_map</var> + as the map the fault originated in, a <var class="Fa">vaddr</var> offset + into the map the fault occurred, and <var class="Fa">access_type</var> + describing the type of access requested. <code class="Fn">uvm_fault</code>() + returns a standard UVM return value.</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="MEMORY_MAPPING_FILES_AND_DEVICES"><a class="permalink" href="#MEMORY_MAPPING_FILES_AND_DEVICES">MEMORY + MAPPING FILES AND DEVICES</a></h1> +<p class="Pp">See <a class="Xr">ubc(9)</a>.</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="VIRTUAL_MEMORY_I/O"><a class="permalink" href="#VIRTUAL_MEMORY_I/O">VIRTUAL + MEMORY I/O</a></h1> +<dl class="Bl-ohang"> + <dt><var class="Ft">int</var></dt> + <dd><code class="Fn">uvm_io</code>(<var class="Fa">struct vm_map *map</var>, + <var class="Fa">struct uio *uio</var>);</dd> +</dl> +<p class="Pp" id="uvm_io"><a class="permalink" href="#uvm_io"><code class="Fn">uvm_io</code></a>() + performs the I/O described in <var class="Fa">uio</var> on the memory + described in <var class="Fa">map</var>.</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="ALLOCATION_OF_KERNEL_MEMORY"><a class="permalink" href="#ALLOCATION_OF_KERNEL_MEMORY">ALLOCATION + OF KERNEL MEMORY</a></h1> +<p class="Pp">See <a class="Xr">uvm_km(9)</a>.</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="ALLOCATION_OF_PHYSICAL_MEMORY"><a class="permalink" href="#ALLOCATION_OF_PHYSICAL_MEMORY">ALLOCATION + OF PHYSICAL MEMORY</a></h1> +<dl class="Bl-ohang"> + <dt><var class="Ft">struct vm_page *</var></dt> + <dd><code class="Fn">uvm_pagealloc</code>(<var class="Fa">struct uvm_object + *uobj</var>, <var class="Fa">voff_t off</var>, <var class="Fa">struct + vm_anon *anon</var>, <var class="Fa">int flags</var>);</dd> + <dt><var class="Ft">void</var></dt> + <dd><code class="Fn">uvm_pagerealloc</code>(<var class="Fa">struct vm_page + *pg</var>, <var class="Fa">struct uvm_object *newobj</var>, + <var class="Fa">voff_t newoff</var>);</dd> + <dt><var class="Ft">void</var></dt> + <dd><code class="Fn">uvm_pagefree</code>(<var class="Fa">struct vm_page + *pg</var>);</dd> + <dt><var class="Ft">int</var></dt> + <dd><code class="Fn">uvm_pglistalloc</code>(<var class="Fa">psize_t + size</var>, <var class="Fa">paddr_t low</var>, <var class="Fa">paddr_t + high</var>, <var class="Fa">paddr_t alignment</var>, + <var class="Fa">paddr_t boundary</var>, <var class="Fa">struct pglist + *rlist</var>, <var class="Fa">int nsegs</var>, <var class="Fa">int + waitok</var>);</dd> + <dt><var class="Ft">void</var></dt> + <dd><code class="Fn">uvm_pglistfree</code>(<var class="Fa">struct pglist + *list</var>);</dd> + <dt><var class="Ft">void</var></dt> + <dd><code class="Fn">uvm_page_physload</code>(<var class="Fa">paddr_t + start</var>, <var class="Fa">paddr_t end</var>, <var class="Fa">paddr_t + avail_start</var>, <var class="Fa">paddr_t avail_end</var>, + <var class="Fa">int free_list</var>);</dd> +</dl> +<p class="Pp" id="uvm_pagealloc"><a class="permalink" href="#uvm_pagealloc"><code class="Fn">uvm_pagealloc</code></a>() + allocates a page of memory at virtual address <var class="Fa">off</var> in + either the object <var class="Fa">uobj</var> or the anonymous memory + <var class="Fa">anon</var>, which must be locked by the caller. Only one of + <var class="Fa">uobj</var> and <var class="Fa">anon</var> can be non + <code class="Dv">NULL</code>. Returns <code class="Dv">NULL</code> when no + page can be found. The flags can be any of</p> +<div class="Bd Pp Li"> +<pre>#define UVM_PGA_USERESERVE 0x0001 /* ok to use reserve pages */ +#define UVM_PGA_ZERO 0x0002 /* returned page must be zero'd */</pre> +</div> +<p class="Pp"><code class="Dv">UVM_PGA_USERESERVE</code> means to allocate a + page even if that will result in the number of free pages being lower than + <code class="Dv">uvmexp.reserve_pagedaemon</code> (if the current thread is + the pagedaemon) or <code class="Dv">uvmexp.reserve_kernel</code> (if the + current thread is not the pagedaemon). <code class="Dv">UVM_PGA_ZERO</code> + causes the returned page to be filled with zeroes, either by allocating it + from a pool of pre-zeroed pages or by zeroing it in-line as necessary.</p> +<p class="Pp" id="uvm_pagerealloc"><a class="permalink" href="#uvm_pagerealloc"><code class="Fn">uvm_pagerealloc</code></a>() + reallocates page <var class="Fa">pg</var> to a new object + <var class="Fa">newobj</var>, at a new offset + <var class="Fa">newoff</var>.</p> +<p class="Pp" id="uvm_pagefree"><a class="permalink" href="#uvm_pagefree"><code class="Fn">uvm_pagefree</code></a>() + frees the physical page <var class="Fa">pg</var>. If the content of the page + is known to be zero-filled, caller should set + <code class="Dv">PG_ZERO</code> in pg->flags so that the page allocator + will use the page to serve future <code class="Dv">UVM_PGA_ZERO</code> + requests efficiently.</p> +<p class="Pp" id="uvm_pglistalloc"><a class="permalink" href="#uvm_pglistalloc"><code class="Fn">uvm_pglistalloc</code></a>() + allocates a list of pages for size <var class="Fa">size</var> byte under + various constraints. <var class="Fa">low</var> and + <var class="Fa">high</var> describe the lowest and highest addresses + acceptable for the list. If <var class="Fa">alignment</var> is non-zero, it + describes the required alignment of the list, in power-of-two notation. If + <var class="Fa">boundary</var> is non-zero, no segment of the list may cross + this power-of-two boundary, relative to zero. <var class="Fa">nsegs</var> is + the maximum number of physically contiguous segments. If + <var class="Fa">waitok</var> is non-zero, the function may sleep until + enough memory is available. (It also may give up in some situations, so a + non-zero <var class="Fa">waitok</var> does not imply that + <code class="Fn">uvm_pglistalloc</code>() cannot return an error.) The + allocated memory is returned in the <var class="Fa">rlist</var> list; the + caller has to provide storage only, the list is initialized by + <code class="Fn">uvm_pglistalloc</code>().</p> +<p class="Pp" id="uvm_pglistfree"><a class="permalink" href="#uvm_pglistfree"><code class="Fn">uvm_pglistfree</code></a>() + frees the list of pages pointed to by <var class="Fa">list</var>. If the + content of the page is known to be zero-filled, caller should set + <code class="Dv">PG_ZERO</code> in pg->flags so that the page allocator + will use the page to serve future <code class="Dv">UVM_PGA_ZERO</code> + requests efficiently.</p> +<p class="Pp" id="uvm_page_physload"><a class="permalink" href="#uvm_page_physload"><code class="Fn">uvm_page_physload</code></a>() + loads physical memory segments into VM space on the specified + <var class="Fa">free_list</var>. It must be called at system boot time to + set up physical memory management pages. The arguments describe the + <var class="Fa">start</var> and <var class="Fa">end</var> of the physical + addresses of the segment, and the available start and end addresses of pages + not already in use. If a system has memory banks of different speeds the + slower memory should be given a higher <var class="Fa">free_list</var> + value.</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="PROCESSES"><a class="permalink" href="#PROCESSES">PROCESSES</a></h1> +<dl class="Bl-ohang"> + <dt><var class="Ft">void</var></dt> + <dd><code class="Fn">uvm_pageout</code>(<var class="Fa">void</var>);</dd> + <dt><var class="Ft">void</var></dt> + <dd><code class="Fn">uvm_scheduler</code>(<var class="Fa">void</var>);</dd> +</dl> +<p class="Pp" id="uvm_pageout"><a class="permalink" href="#uvm_pageout"><code class="Fn">uvm_pageout</code></a>() + is the main loop for the page daemon.</p> +<p class="Pp" id="uvm_scheduler"><a class="permalink" href="#uvm_scheduler"><code class="Fn">uvm_scheduler</code></a>() + is the process zero main loop, which is to be called after the system has + finished starting other processes. It handles the swapping in of runnable, + swapped out processes in priority order.</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="PAGE_LOAN"><a class="permalink" href="#PAGE_LOAN">PAGE + LOAN</a></h1> +<dl class="Bl-ohang"> + <dt><var class="Ft">int</var></dt> + <dd><code class="Fn">uvm_loan</code>(<var class="Fa">struct vm_map *map</var>, + <var class="Fa">vaddr_t start</var>, <var class="Fa">vsize_t len</var>, + <var class="Fa">void *v</var>, <var class="Fa">int flags</var>);</dd> + <dt><var class="Ft">void</var></dt> + <dd><code class="Fn">uvm_unloan</code>(<var class="Fa">void *v</var>, + <var class="Fa">int npages</var>, <var class="Fa">int flags</var>);</dd> +</dl> +<p class="Pp" id="uvm_loan"><a class="permalink" href="#uvm_loan"><code class="Fn">uvm_loan</code></a>() + loans pages in a map out to anons or to the kernel. + <var class="Fa">map</var> should be unlocked, <var class="Fa">start</var> + and <var class="Fa">len</var> should be multiples of + <code class="Dv">PAGE_SIZE</code>. Argument <var class="Fa">flags</var> + should be one of</p> +<div class="Bd Pp Li"> +<pre>#define UVM_LOAN_TOANON 0x01 /* loan to anons */ +#define UVM_LOAN_TOPAGE 0x02 /* loan to kernel */</pre> +</div> +<p class="Pp" id="uvm_loan~2"><var class="Fa">v</var> should be pointer to array + of pointers to <code class="Li">struct anon</code> or + <code class="Li">struct vm_page</code>, as appropriate. The caller has to + allocate memory for the array and ensure it's big enough to hold + <var class="Fa">len / PAGE_SIZE</var> pointers. Returns 0 for success, or + appropriate error number otherwise. Note that wired pages can't be loaned + out and + <a class="permalink" href="#uvm_loan~2"><code class="Fn">uvm_loan</code></a>() + will fail in that case.</p> +<p class="Pp" id="uvm_unloan"><a class="permalink" href="#uvm_unloan"><code class="Fn">uvm_unloan</code></a>() + kills loans on pages or anons. The <var class="Fa">v</var> must point to the + array of pointers initialized by previous call to + <code class="Fn">uvm_loan</code>(). <var class="Fa">npages</var> should + match number of pages allocated for loan, this also matches number of items + in the array. Argument <var class="Fa">flags</var> should be one of</p> +<div class="Bd Pp Li"> +<pre>#define UVM_LOAN_TOANON 0x01 /* loan to anons */ +#define UVM_LOAN_TOPAGE 0x02 /* loan to kernel */</pre> +</div> +<p class="Pp" id="uvm_loan~3">and should match what was used for previous call + to + <a class="permalink" href="#uvm_loan~3"><code class="Fn">uvm_loan</code></a>().</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="MISCELLANEOUS_FUNCTIONS"><a class="permalink" href="#MISCELLANEOUS_FUNCTIONS">MISCELLANEOUS + FUNCTIONS</a></h1> +<dl class="Bl-ohang"> + <dt><var class="Ft">struct uvm_object *</var></dt> + <dd><code class="Fn">uao_create</code>(<var class="Fa">vsize_t size</var>, + <var class="Fa">int flags</var>);</dd> + <dt><var class="Ft">void</var></dt> + <dd><code class="Fn">uao_detach</code>(<var class="Fa">struct uvm_object + *uobj</var>);</dd> + <dt><var class="Ft">void</var></dt> + <dd><code class="Fn">uao_reference</code>(<var class="Fa">struct uvm_object + *uobj</var>);</dd> + <dt><var class="Ft">bool</var></dt> + <dd><code class="Fn">uvm_chgkprot</code>(<var class="Fa">void *addr</var>, + <var class="Fa">size_t len</var>, <var class="Fa">int rw</var>);</dd> + <dt><var class="Ft">void</var></dt> + <dd><code class="Fn">uvm_kernacc</code>(<var class="Fa">void *addr</var>, + <var class="Fa">size_t len</var>, <var class="Fa">int rw</var>);</dd> + <dt><var class="Ft">int</var></dt> + <dd><code class="Fn">uvm_vslock</code>(<var class="Fa">struct vmspace + *vs</var>, <var class="Fa">void *addr</var>, <var class="Fa">size_t + len</var>, <var class="Fa">vm_prot_t prot</var>);</dd> + <dt><var class="Ft">void</var></dt> + <dd><code class="Fn">uvm_vsunlock</code>(<var class="Fa">struct vmspace + *vs</var>, <var class="Fa">void *addr</var>, <var class="Fa">size_t + len</var>);</dd> + <dt><var class="Ft">void</var></dt> + <dd><code class="Fn">uvm_meter</code>(<var class="Fa">void</var>);</dd> + <dt><var class="Ft">void</var></dt> + <dd><code class="Fn">uvm_proc_fork</code>(<var class="Fa">struct proc + *p1</var>, <var class="Fa">struct proc *p2</var>, <var class="Fa">bool + shared</var>);</dd> + <dt><var class="Ft">int</var></dt> + <dd><code class="Fn">uvm_grow</code>(<var class="Fa">struct proc *p</var>, + <var class="Fa">vaddr_t sp</var>);</dd> + <dt><var class="Ft">void</var></dt> + <dd><code class="Fn">uvn_findpages</code>(<var class="Fa">struct uvm_object + *uobj</var>, <var class="Fa">voff_t offset</var>, <var class="Fa">int + *npagesp</var>, <var class="Fa">struct vm_page **pps</var>, + <var class="Fa">int flags</var>);</dd> + <dt><var class="Ft">void</var></dt> + <dd><code class="Fn">uvm_vnp_setsize</code>(<var class="Fa">struct vnode + *vp</var>, <var class="Fa">voff_t newsize</var>);</dd> +</dl> +<p class="Pp" id="uao_create">The + <a class="permalink" href="#uao_create"><code class="Fn">uao_create</code></a>(), + <a class="permalink" href="#uao_detach"><code class="Fn" id="uao_detach">uao_detach</code></a>(), + and <code class="Fn">uao_reference</code>() functions operate on anonymous + memory objects, such as those used to support System V shared memory. + <code class="Fn">uao_create</code>() returns an object of size + <var class="Fa">size</var> with flags:</p> +<div class="Bd Pp Li"> +<pre>#define UAO_FLAG_KERNOBJ 0x1 /* create kernel object */ +#define UAO_FLAG_KERNSWAP 0x2 /* enable kernel swap */</pre> +</div> +<p class="Pp" id="uao_reference">which can only be used once each at system boot + time. + <a class="permalink" href="#uao_reference"><code class="Fn">uao_reference</code></a>() + creates an additional reference to the named anonymous memory object. + <a class="permalink" href="#uao_detach~2"><code class="Fn" id="uao_detach~2">uao_detach</code></a>() + removes a reference from the named anonymous memory object, destroying it if + removing the last reference.</p> +<p class="Pp" id="uvm_chgkprot"><a class="permalink" href="#uvm_chgkprot"><code class="Fn">uvm_chgkprot</code></a>() + changes the protection of kernel memory from <var class="Fa">addr</var> to + <var class="Fa">addr + len</var> to the value of <var class="Fa">rw</var>. + This is primarily useful for debuggers, for setting breakpoints. This + function is only available with options <code class="Dv">KGDB</code>.</p> +<p class="Pp" id="uvm_kernacc"><a class="permalink" href="#uvm_kernacc"><code class="Fn">uvm_kernacc</code></a>() + checks the access at address <var class="Fa">addr</var> to + <var class="Fa">addr + len</var> for <var class="Fa">rw</var> access in the + kernel address space.</p> +<p class="Pp" id="uvm_vslock"><a class="permalink" href="#uvm_vslock"><code class="Fn">uvm_vslock</code></a>() + and + <a class="permalink" href="#uvm_vsunlock"><code class="Fn" id="uvm_vsunlock">uvm_vsunlock</code></a>() + control the wiring and unwiring of pages for process <var class="Fa">p</var> + from <var class="Fa">addr</var> to <var class="Fa">addr + len</var>. These + functions are normally used to wire memory for I/O.</p> +<p class="Pp" id="uvm_meter"><a class="permalink" href="#uvm_meter"><code class="Fn">uvm_meter</code></a>() + calculates the load average.</p> +<p class="Pp" id="uvm_proc_fork"><a class="permalink" href="#uvm_proc_fork"><code class="Fn">uvm_proc_fork</code></a>() + forks a virtual address space for process' (old) <var class="Fa">p1</var> + and (new) <var class="Fa">p2</var>. If the <var class="Fa">shared</var> + argument is non zero, p1 shares its address space with p2, otherwise a new + address space is created. This function currently has no return value, and + thus cannot fail. In the future, this function will be changed to allow it + to fail in low memory conditions.</p> +<p class="Pp" id="uvm_grow"><a class="permalink" href="#uvm_grow"><code class="Fn">uvm_grow</code></a>() + increases the stack segment of process <var class="Fa">p</var> to include + <var class="Fa">sp</var>.</p> +<p class="Pp" id="uvn_findpages"><a class="permalink" href="#uvn_findpages"><code class="Fn">uvn_findpages</code></a>() + looks up or creates pages in <var class="Fa">uobj</var> at offset + <var class="Fa">offset</var>, marks them busy and returns them in the + <var class="Fa">pps</var> array. Currently <var class="Fa">uobj</var> must + be a vnode object. The number of pages requested is pointed to by + <var class="Fa">npagesp</var>, and this value is updated with the actual + number of pages returned. The flags can be any bitwise inclusive-or of:</p> +<p class="Pp"></p> +<div class="Bd-indent"> +<dl class="Bl-tag Bl-compact"> + <dt id="UFP_ALL"><a class="permalink" href="#UFP_ALL"><code class="Dv">UFP_ALL</code></a></dt> + <dd>Zero pseudo-flag meaning return all pages.</dd> + <dt id="UFP_NOWAIT"><a class="permalink" href="#UFP_NOWAIT"><code class="Dv">UFP_NOWAIT</code></a></dt> + <dd>Don't sleep — yield <code class="Dv">NULL</code> for busy pages or + for uncached pages for which allocation would sleep.</dd> + <dt id="UFP_NOALLOC"><a class="permalink" href="#UFP_NOALLOC"><code class="Dv">UFP_NOALLOC</code></a></dt> + <dd>Don't allocate — yield <code class="Dv">NULL</code> for uncached + pages.</dd> + <dt id="UFP_NOCACHE"><a class="permalink" href="#UFP_NOCACHE"><code class="Dv">UFP_NOCACHE</code></a></dt> + <dd>Don't use cached pages — yield <code class="Dv">NULL</code> + instead.</dd> + <dt id="UFP_NORDONLY"><a class="permalink" href="#UFP_NORDONLY"><code class="Dv">UFP_NORDONLY</code></a></dt> + <dd>Don't yield read-only pages — yield <code class="Dv">NULL</code> + for pages marked <code class="Dv">PG_READONLY</code>.</dd> + <dt id="UFP_DIRTYONLY"><a class="permalink" href="#UFP_DIRTYONLY"><code class="Dv">UFP_DIRTYONLY</code></a></dt> + <dd>Don't yield clean pages — stop early at the first clean one. As a + side effect, mark yielded dirty pages clean. Caller must write them to + permanent storage before unbusying.</dd> + <dt id="UFP_BACKWARD"><a class="permalink" href="#UFP_BACKWARD"><code class="Dv">UFP_BACKWARD</code></a></dt> + <dd>Traverse pages in reverse order. If + <a class="permalink" href="#uvn_findpages~2"><code class="Fn" id="uvn_findpages~2">uvn_findpages</code></a>() + returns early, it will have filled + <code class="Li">*</code><var class="Fa">npagesp</var> entries at the end + of <var class="Fa">pps</var> rather than the beginning.</dd> +</dl> +</div> +<p class="Pp" id="uvm_vnp_setsize"><a class="permalink" href="#uvm_vnp_setsize"><code class="Fn">uvm_vnp_setsize</code></a>() + sets the size of vnode <var class="Fa">vp</var> to + <var class="Fa">newsize</var>. Caller must hold a reference to the vnode. If + the vnode shrinks, pages no longer used are discarded.</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="MISCELLANEOUS_MACROS"><a class="permalink" href="#MISCELLANEOUS_MACROS">MISCELLANEOUS + MACROS</a></h1> +<dl class="Bl-ohang"> + <dt><var class="Ft">paddr_t</var></dt> + <dd><code class="Fn">atop</code>(<var class="Fa">paddr_t pa</var>);</dd> + <dt><var class="Ft">paddr_t</var></dt> + <dd><code class="Fn">ptoa</code>(<var class="Fa">paddr_t pn</var>);</dd> + <dt><var class="Ft">paddr_t</var></dt> + <dd><code class="Fn">round_page</code>(<var class="Fa">address</var>);</dd> + <dt><var class="Ft">paddr_t</var></dt> + <dd><code class="Fn">trunc_page</code>(<var class="Fa">address</var>);</dd> +</dl> +<p class="Pp" id="atop">The + <a class="permalink" href="#atop"><code class="Fn">atop</code></a>() macro + converts a physical address <var class="Fa">pa</var> into a page number. The + <a class="permalink" href="#ptoa"><code class="Fn" id="ptoa">ptoa</code></a>() + macro does the opposite by converting a page number <var class="Fa">pn</var> + into a physical address.</p> +<p class="Pp" id="round_page"><a class="permalink" href="#round_page"><code class="Fn">round_page</code></a>() + and + <a class="permalink" href="#trunc_page"><code class="Fn" id="trunc_page">trunc_page</code></a>() + macros return a page address boundary from rounding + <var class="Fa">address</var> up and down, respectively, to the nearest page + boundary. These macros work for either addresses or byte counts.</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="SYSCTL"><a class="permalink" href="#SYSCTL">SYSCTL</a></h1> +<p class="Pp">UVM provides support for the <code class="Dv">CTL_VM</code> domain + of the <a class="Xr">sysctl(3)</a> hierarchy. It handles the + <code class="Dv">VM_LOADAVG</code>, <code class="Dv">VM_METER</code>, + <code class="Dv">VM_UVMEXP</code>, and <code class="Dv">VM_UVMEXP2</code> + nodes, which return the current load averages, calculates current VM totals, + returns the uvmexp structure, and a kernel version independent view of the + uvmexp structure, respectively. It also exports a number of tunables that + control how much VM space is allowed to be consumed by various tasks. The + load averages are typically accessed from userland using the + <a class="Xr">getloadavg(3)</a> function. The uvmexp structure has all + global state of the UVM system, and has the following members:</p> +<div class="Bd Pp Li"> +<pre>/* vm_page constants */ +int pagesize; /* size of a page (PAGE_SIZE): must be power of 2 */ +int pagemask; /* page mask */ +int pageshift; /* page shift */ + +/* vm_page counters */ +int npages; /* number of pages we manage */ +int free; /* number of free pages */ +int paging; /* number of pages in the process of being paged out */ +int wired; /* number of wired pages */ +int reserve_pagedaemon; /* number of pages reserved for pagedaemon */ +int reserve_kernel; /* number of pages reserved for kernel */ + +/* pageout params */ +int freemin; /* min number of free pages */ +int freetarg; /* target number of free pages */ +int inactarg; /* target number of inactive pages */ +int wiredmax; /* max number of wired pages */ + +/* swap */ +int nswapdev; /* number of configured swap devices in system */ +int swpages; /* number of PAGE_SIZE'ed swap pages */ +int swpginuse; /* number of swap pages in use */ +int nswget; /* number of times fault calls uvm_swap_get() */ +int nanon; /* number total of anon's in system */ +int nfreeanon; /* number of free anon's */ + +/* stat counters */ +int faults; /* page fault count */ +int traps; /* trap count */ +int intrs; /* interrupt count */ +int swtch; /* context switch count */ +int softs; /* software interrupt count */ +int syscalls; /* system calls */ +int pageins; /* pagein operation count */ + /* pageouts are in pdpageouts below */ +int pgswapin; /* pages swapped in */ +int pgswapout; /* pages swapped out */ +int forks; /* forks */ +int forks_ppwait; /* forks where parent waits */ +int forks_sharevm; /* forks where vmspace is shared */ + +/* fault subcounters */ +int fltnoram; /* number of times fault was out of ram */ +int fltnoanon; /* number of times fault was out of anons */ +int fltpgwait; /* number of times fault had to wait on a page */ +int fltpgrele; /* number of times fault found a released page */ +int fltrelck; /* number of times fault relock called */ +int fltrelckok; /* number of times fault relock is a success */ +int fltanget; /* number of times fault gets anon page */ +int fltanretry; /* number of times fault retrys an anon get */ +int fltamcopy; /* number of times fault clears "needs copy" */ +int fltnamap; /* number of times fault maps a neighbor anon page */ +int fltnomap; /* number of times fault maps a neighbor obj page */ +int fltlget; /* number of times fault does a locked pgo_get */ +int fltget; /* number of times fault does an unlocked get */ +int flt_anon; /* number of times fault anon (case 1a) */ +int flt_acow; /* number of times fault anon cow (case 1b) */ +int flt_obj; /* number of times fault is on object page (2a) */ +int flt_prcopy; /* number of times fault promotes with copy (2b) */ +int flt_przero; /* number of times fault promotes with zerofill (2b) */ + +/* daemon counters */ +int pdwoke; /* number of times daemon woke up */ +int pdrevs; /* number of times daemon rev'd clock hand */ +int pdfreed; /* number of pages daemon freed since boot */ +int pdscans; /* number of pages daemon scanned since boot */ +int pdanscan; /* number of anonymous pages scanned by daemon */ +int pdobscan; /* number of object pages scanned by daemon */ +int pdreact; /* number of pages daemon reactivated since boot */ +int pdbusy; /* number of times daemon found a busy page */ +int pdpageouts; /* number of times daemon started a pageout */ +int pddeact; /* number of pages daemon deactivates */</pre> +</div> +</section> +<section class="Sh"> +<h1 class="Sh" id="NOTES"><a class="permalink" href="#NOTES">NOTES</a></h1> +<p class="Pp"><code class="Fn">uvm_chgkprot</code>() is only available if the + kernel has been compiled with options <code class="Dv">KGDB</code>.</p> +<p class="Pp">All structure and types whose names begin with “vm_” + will be renamed to “uvm_”.</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE + ALSO</a></h1> +<p class="Pp"><a class="Xr">swapctl(2)</a>, <a class="Xr">getloadavg(3)</a>, + <a class="Xr">kvm(3)</a>, <a class="Xr">sysctl(3)</a>, + <a class="Xr">ddb(4)</a>, <a class="Xr">options(4)</a>, + <a class="Xr">memoryallocators(9)</a>, <a class="Xr">pmap(9)</a>, + <a class="Xr">ubc(9)</a>, <a class="Xr">uvm_km(9)</a>, + <a class="Xr">uvm_map(9)</a></p> +<p class="Pp"><cite class="Rs"><span class="RsA">Charles D. Cranor</span> and + <span class="RsA">Gurudatta M. Parulkar</span>, <span class="RsT">The UVM + Virtual Memory System</span>, <i class="RsB">Proceedings of the USENIX + Annual Technical Conference</i>, <i class="RsI">USENIX Association</i>, + <a class="RsU" href="http://www.usenix.org/event/usenix99/full_papers/cranor/cranor.pdf">http://www.usenix.org/event/usenix99/full_papers/cranor/cranor.pdf</a>, + <span class="RsP">117-130</span>, <span class="RsD">June 6-11, + 1999</span>.</cite></p> +</section> +<section class="Sh"> +<h1 class="Sh" id="HISTORY"><a class="permalink" href="#HISTORY">HISTORY</a></h1> +<p class="Pp">UVM is a new VM system developed at Washington University in St. + Louis (Missouri). UVM's roots lie partly in the Mach-based + <span class="Ux">4.4BSD</span> VM system, the + <span class="Ux">FreeBSD</span> VM system, and the SunOS 4 VM system. UVM's + basic structure is based on the <span class="Ux">4.4BSD</span> VM system. + UVM's new anonymous memory system is based on the anonymous memory system + found in the SunOS 4 VM (as described in papers published by Sun + Microsystems, Inc.). UVM also includes a number of features new to + <span class="Ux">BSD</span> including page loanout, map entry passing, + simplified copy-on-write, and clustered anonymous memory pageout. UVM is + also further documented in an August 1998 dissertation by Charles D. + Cranor.</p> +<p class="Pp">UVM appeared in <span class="Ux">NetBSD 1.4</span>.</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="AUTHORS"><a class="permalink" href="#AUTHORS">AUTHORS</a></h1> +<p class="Pp"><span class="An">Charles D. Cranor</span> + <<a class="Mt" href="mailto:chuck@ccrc.wustl.edu">chuck@ccrc.wustl.edu</a>> + designed and implemented UVM.</p> +<p class="Pp"><span class="An">Matthew Green</span> + <<a class="Mt" href="mailto:mrg@eterna23.net">mrg@eterna23.net</a>> + wrote the swap-space management code and handled the logistical issues + involved with merging UVM into the <span class="Ux">NetBSD</span> source + tree.</p> +<p class="Pp"><span class="An">Chuck Silvers</span> + <<a class="Mt" href="mailto:chuq@chuq.com">chuq@chuq.com</a>> + implemented the aobj pager, thus allowing UVM to support System V shared + memory and process swapping.</p> +</section> +</div> +<table class="foot"> + <tr> + <td class="foot-date">March 23, 2015</td> + <td class="foot-os">NetBSD 10.1</td> + </tr> +</table> |