Hi Andi, On 05/06/2015 02:57 PM, Andi Kleen wrote: > On Wed, May 06, 2015 at 02:31:58PM +0200, Michael Kerrisk (man-pages) wrote: >> Hi Andi, >> >> Brice's patch seems broadly okay to me, but you originally wrote the >> pages, so I'd be happy if you could comment. Could you take a look please? > > Just s/process/thread/g ? No, it doesn't seem to be quite that. Brice, can you say a little more here? > The distinction between process and thread is fuzzy in Linux of course, > but i suppose it matches the user's terms better. > > Fine for me. Okay -- I'll await further input from Brice, and then apply. Cheers, Michael >> Cheers, >> >> Michael >> >> >> On 04/30/2015 12:31 PM, Brice Goglin wrote: >>> Hello, >>> >>> set/get_mempolicy manpages say that the memory allocation policy is >>> per process while reading the code and testing shows that it's actually >>> per thread. >>> Here's a quick fix, which may need to be improved to better explain that we're >>> allocating in the context of a thread within a process address space. >>> >>> Brice >>> >>> >>> >>> >>> >>> >>> set/get_mempolicy.2: policy is per thread, not per process >>> >>> Signed-off-by: Brice Goglin <Brice.Goglin@xxxxxxxx> >>> >>> diff --git a/man2/get_mempolicy.2 b/man2/get_mempolicy.2 >>> index a17c0f3..c0e9639 100644 >>> --- a/man2/get_mempolicy.2 >>> +++ b/man2/get_mempolicy.2 >>> @@ -26,7 +26,7 @@ >>> .\" >>> .TH GET_MEMPOLICY 2 2008-08-15 Linux "Linux Programmer's Manual" >>> .SH NAME >>> -get_mempolicy \- retrieve NUMA memory policy for a process >>> +get_mempolicy \- retrieve NUMA memory policy for a thread >>> .SH SYNOPSIS >>> .B "#include <numaif.h>" >>> .nf >>> @@ -39,19 +39,19 @@ Link with \fI\-lnuma\fP. >>> .fi >>> .SH DESCRIPTION >>> .BR get_mempolicy () >>> -retrieves the NUMA policy of the calling process or of a memory address, >>> +retrieves the NUMA policy of the calling thread or of a memory address, >>> depending on the setting of >>> .IR flags . >>> >>> A NUMA machine has different >>> memory controllers with different distances to specific CPUs. >>> The memory policy defines from which node memory is allocated for >>> -the process. >>> +the thread. >>> >>> If >>> .I flags >>> is specified as 0, >>> -then information about the calling process's default policy >>> +then information about the calling thread's default policy >>> (as set by >>> .BR set_mempolicy (2)) >>> is returned. >>> @@ -59,7 +59,7 @@ The policy returned >>> .RI [ mode >>> and >>> .IR nodemask ] >>> -may be used to restore the process's policy to its state at >>> +may be used to restore the thread's policy to its state at >>> the time of the call to >>> .BR get_mempolicy () >>> using >>> @@ -72,7 +72,7 @@ specifies >>> (available since Linux 2.6.24), the >>> .I mode >>> argument is ignored and the set of nodes [memories] that the >>> -process is allowed to specify in subsequent calls to >>> +thread is allowed to specify in subsequent calls to >>> .BR mbind (2) >>> or >>> .BR set_mempolicy (2) >>> @@ -94,7 +94,7 @@ specifies >>> then information is returned about the policy governing the memory >>> address given in >>> .IR addr . >>> -This policy may be different from the process's default policy if >>> +This policy may be different from the thread's default policy if >>> .BR mbind (2) >>> or one of the helper functions described in >>> .BR numa (3) >>> @@ -135,7 +135,7 @@ is allocated into the location pointed to by >>> .IR mode . >>> If no page has yet been allocated for the specified address, >>> .BR get_mempolicy () >>> -will allocate a page as if the process had performed a read >>> +will allocate a page as if the thread had performed a read >>> [load] access to that address, and return the ID of the node >>> where that page was allocated. >>> >>> @@ -145,7 +145,7 @@ specifies >>> .BR MPOL_F_NODE , >>> but not >>> .BR MPOL_F_ADDR , >>> -and the process's current policy is >>> +and the thread's current policy is >>> .BR MPOL_INTERLEAVE , >>> then >>> .BR get_mempolicy () >>> @@ -153,7 +153,7 @@ will return in the location pointed to by a non-NULL >>> .I mode >>> argument, >>> the node ID of the next node that will be used for >>> -interleaving of internal kernel pages allocated on behalf of the process. >>> +interleaving of internal kernel pages allocated on behalf of the thread. >>> .\" Note: code returns next interleave node via 'mode' argument -Lee Schermerhorn >>> These allocations include pages for memory-mapped files in >>> process memory ranges mapped using the >>> @@ -214,7 +214,7 @@ specified >>> .B MPOL_F_NODE >>> but not >>> .B MPOL_F_ADDR >>> -and the current process policy is not >>> +and the current thread policy is not >>> .BR MPOL_INTERLEAVE . >>> Or, >>> .I flags >>> diff --git a/man2/set_mempolicy.2 b/man2/set_mempolicy.2 >>> index 9d7d1de..f5169da 100644 >>> --- a/man2/set_mempolicy.2 >>> +++ b/man2/set_mempolicy.2 >>> @@ -26,7 +26,7 @@ >>> .\" >>> .TH SET_MEMPOLICY 2 2014-05-28 Linux "Linux Programmer's Manual" >>> .SH NAME >>> -set_mempolicy \- set default NUMA memory policy for a process and its children >>> +set_mempolicy \- set default NUMA memory policy for a thread and its children >>> .SH SYNOPSIS >>> .nf >>> .B "#include <numaif.h>" >>> @@ -38,7 +38,7 @@ Link with \fI\-lnuma\fP. >>> .fi >>> .SH DESCRIPTION >>> .BR set_mempolicy () >>> -sets the NUMA memory policy of the calling process, >>> +sets the NUMA memory policy of the calling thread, >>> which consists of a policy mode and zero or more nodes, >>> to the values specified by the >>> .IR mode , >>> @@ -50,28 +50,28 @@ arguments. >>> A NUMA machine has different >>> memory controllers with different distances to specific CPUs. >>> The memory policy defines from which node memory is allocated for >>> -the process. >>> +the thread. >>> >>> -This system call defines the default policy for the process. >>> -The process policy governs allocation of pages in the process's >>> +This system call defines the default policy for the thread. >>> +The thread policy governs allocation of pages in the process's >>> address space outside of memory ranges >>> controlled by a more specific policy set by >>> .BR mbind (2). >>> -The process default policy also controls allocation of any pages for >>> +The thread default policy also controls allocation of any pages for >>> memory-mapped files mapped using the >>> .BR mmap (2) >>> call with the >>> .B MAP_PRIVATE >>> -flag and that are only read [loaded] from by the process >>> +flag and that are only read [loaded] from by the thread >>> and of memory-mapped files mapped using the >>> .BR mmap (2) >>> call with the >>> .B MAP_SHARED >>> flag, regardless of the access type. >>> The policy is applied only when a new page is allocated >>> -for the process. >>> +for the thread. >>> For anonymous memory this is when the page is first >>> -touched by the application. >>> +touched by the thread. >>> >>> The >>> .I mode >>> @@ -154,7 +154,7 @@ cpuset context includes one or more of the nodes specified by >>> >>> The >>> .B MPOL_DEFAULT >>> -mode specifies that any nondefault process memory policy be removed, >>> +mode specifies that any nondefault thread memory policy be removed, >>> so that the memory policy "falls back" to the system default policy. >>> The system default policy is "local allocation"\(emthat is, >>> allocate memory on the node of the CPU that triggered the allocation. >>> @@ -211,9 +211,9 @@ arguments specify the empty set, then the policy >>> specifies "local allocation" >>> (like the system default policy discussed above). >>> >>> -The process memory policy is preserved across an >>> +The thread memory policy is preserved across an >>> .BR execve (2), >>> -and is inherited by child processes created using >>> +and is inherited by child threads created using >>> .BR fork (2) >>> or >>> .BR clone (2). >>> @@ -279,9 +279,9 @@ system call was added to the Linux kernel in version 2.6.7. >>> .SH CONFORMING TO >>> This system call is Linux-specific. >>> .SH NOTES >>> -Process policy is not remembered if the page is swapped out. >>> +Memory policy is not remembered if the page is swapped out. >>> When such a page is paged back in, it will use the policy of >>> -the process or memory range that is in effect at the time the >>> +the thread or memory range that is in effect at the time the >>> page is allocated. >>> >>> For information on library support, see >>> >>> >> >> >> -- >> Michael Kerrisk >> Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ >> Linux/UNIX System Programming Training: http://man7.org/training/ >> > -- Michael Kerrisk Linux man-pages 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