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? 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/ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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