On 10/25/2016 05:40 PM, Piotr Kwapulinski wrote: > Hi Michael, > > I spent a couple of hours trying to review your patch. Unfortunately > nowadays I spend no more than an hour per day for whole my linux > kernel activity. It may take longer time for me to review it. > This patch touches some areas of the kernel I'm still not an expert of > (though I'm learning a lot). I'll review (and possibly fix) it ASAP. Okay, Piotr, Thanks. If you do eventually have some input, that would be great, but I understand you are time constrained. Cheers, Michael > On Thu, Oct 13, 2016 at 10:38:33AM +0200, Michael Kerrisk (man-pages) wrote: >> Christoph, Piotr, and Brice >> >> Since you (Christoph and Piotr) helped with documenting MPOL_LOCAL >> just recently, I wonder if I might ask you to review a patch that I >> propose for the mbind(2) manual page. >> >> As far as I understand, memory policy, as set by set_mempolicy(2) >> is a per-thread attribute. The set_mempolicy(2) and get_mempolicy(2) >> pages already reflect this, thanks to a patch from Brice last year. >> >> However, such changes were not made in the mbind(2) page. >> I wonder if I could ask you (and Brice, and anyone who's willing) >> to look at the patch that I propose below to remedy this. (There are >> a couple questions "???" that I've injected in the patch.) Is it okay? >> >> Cheers, >> >> Michael >> >> >> diff --git a/man2/mbind.2 b/man2/mbind.2 >> index a5f26e2..9494854 100644 >> --- a/man2/mbind.2 >> +++ b/man2/mbind.2 >> @@ -75,16 +75,16 @@ page in the kernel containing all zeros. >> For a file mapped with >> .BR MAP_PRIVATE , >> an initial read access will allocate pages according to the >> -process policy of the process that causes the page to be allocated. >> -This may not be the process that called >> +memory policy of the thread that causes the page to be allocated. >> +This may not be the thread that called >> .BR mbind (). >> >> The specified policy will be ignored for any >> .B MAP_SHARED >> mappings in the specified memory range. >> -Rather the pages will be allocated according to the process policy >> -of the process that caused the page to be allocated. >> -Again, this may not be the process that called >> +Rather the pages will be allocated according to the memory policy >> +of the thread that caused the page to be allocated. >> +Again, this may not be the thread that called >> .BR mbind (). >> >> If the specified memory range includes a shared memory region >> @@ -100,7 +100,10 @@ If, however, the shared memory region was created with the >> .B SHM_HUGETLB >> flag, >> the huge pages will be allocated according to the policy specified >> -only if the page allocation is caused by the process that calls >> +only if the page allocation is caused by the thread that calls >> +.\" >> +.\" ??? Is it correct to change "process" to "thread" in the preceding line? >> +.\" >> .BR mbind () >> for that region. >> >> @@ -146,15 +149,15 @@ A nonempty >> specifies physical node IDs. >> Linux does not remap the >> .I nodemask >> -when the process moves to a different cpuset context, >> -nor when the set of nodes allowed by the process's >> +when the thread moves to a different cpuset context, >> +nor when the set of nodes allowed by the thread's >> current cpuset context changes. >> .TP >> .BR MPOL_F_RELATIVE_NODES " (since Linux-2.6.26)" >> A nonempty >> .I nodemask >> specifies node IDs that are relative to the set of >> -node IDs allowed by the process's current cpuset. >> +node IDs allowed by the thread's current cpuset. >> .PP >> .I nodemask >> points to a bit mask of nodes containing up to >> @@ -178,7 +181,7 @@ argument is ignored. >> Where a >> .I nodemask >> is required, it must contain at least one node that is on-line, >> -allowed by the process's current cpuset context >> +allowed by the thread's current cpuset context >> (unless the >> .B MPOL_F_STATIC_NODES >> mode flag is specified), >> @@ -194,10 +197,10 @@ mode requests that any nondefault policy be removed, >> restoring default behavior. >> When applied to a range of memory via >> .BR mbind (), >> -this means to use the process policy, >> +this means to use the thread memory policy, >> which may have been set with >> .BR set_mempolicy (2). >> -If the mode of the process policy is also >> +If the mode of the thread memory policy is also >> .BR MPOL_DEFAULT , >> the system-wide default policy will be used. >> The system-wide default policy allocates >> @@ -268,13 +271,13 @@ If the "local node" is low on free memory, >> the kernel will try to allocate memory from other nodes. >> The kernel will allocate memory from the "local node" >> whenever memory for this node is available. >> -If the "local node" is not allowed by the process's current cpuset context, >> +If the "local node" is not allowed by the thread's current cpuset context, >> the kernel will try to allocate memory from other nodes. >> The kernel will allocate memory from the "local node" whenever >> -it becomes allowed by the process's current cpuset context. >> +it becomes allowed by the thread's current cpuset context. >> By contrast, >> .B MPOL_DEFAULT >> -reverts to the policy of the process (which may be set via >> +reverts to the memory policy of the thread (which may be set via >> .BR set_mempolicy (2)); >> that policy may be something other than "local allocation". >> .PP >> @@ -300,7 +303,10 @@ is specified in >> .IR flags , >> then the kernel will attempt to move all the existing pages >> in the memory range so that they follow the policy. >> -Pages that are shared with other processes will not be moved. >> +Pages that are shared with other threads will not be moved. >> +.\" >> +.\" ??? Is it correct to change "processes" to "threads" in the preceding line? >> +.\" >> If >> .B MPOL_MF_STRICT >> is also specified, then the call will fail with the error >> @@ -312,8 +318,11 @@ If >> is passed in >> .IR flags , >> then the kernel will attempt to move all existing pages in the memory range >> -regardless of whether other processes use the pages. >> -The calling process must be privileged >> +regardless of whether other threads use the pages. >> +.\" >> +.\" ??? Is it correct to change "processes" to "threads" in the preceding line? >> +.\" >> +The calling thread must be privileged >> .RB ( CAP_SYS_NICE ) >> to use this flag. >> If >> @@ -383,7 +392,7 @@ specifies one or more node IDs that are >> greater than the maximum supported node ID. >> Or, none of the node IDs specified by >> .I nodemask >> -are on-line and allowed by the process's current cpuset context, >> +are on-line and allowed by the thread's current cpuset context, >> or none of the specified nodes contain memory. >> Or, the >> .I mode >> @@ -440,14 +449,14 @@ When >> .B MPOL_DEFAULT >> is specified for >> .BR set_mempolicy (2), >> -the process's policy reverts to system default policy >> +the thread's memory policy reverts to the system default policy >> or local allocation. >> When >> .B MPOL_DEFAULT >> is specified for a range of memory using >> .BR mbind (), >> any pages subsequently allocated for that range will use >> -the process's policy, as set by >> +the thread's memory policy, as set by >> .BR set_mempolicy (2). >> This effectively removes the explicit policy from the >> specified range, "falling back" to a possibly nondefault >> >> -- >> 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 maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
