From: Matthew Cassell Date: Thu, 20 Feb 2025 22:52:32 +0000 (-0600) Subject: man/man2/{mbind,set_mempolicy}.2: Document MPOL_PREFERRED_MANY X-Git-Tag: man-pages-6.12~1 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fe7e094e78139a4ac5ee31b2321b77041c725794;p=thirdparty%2Fman-pages.git man/man2/{mbind,set_mempolicy}.2: Document MPOL_PREFERRED_MANY Browsing a header file in the kernel source and saw the memory policy enum used for mbind() and set_mempolicy() using an entry that I didn't recognize. I man 2'd both system calls and didn't see an entry for MPOL_PREFERRED_MANY. The commit on the enum entry: linux.git b27abaccf8e8 (2021-09-02; "mm/mempolicy: add MPOL_PREFERRED_MANY for multiple preferred nodes") The commit message gives the rationale as to why the MPOL_PREFERRED_MANY mode would be beneficial. Giving the ability to set the memory policy to target different tiers of memory over various NUMA nodes. Cc: Dave Hansen Signed-off-by: Matthew Cassell Message-ID: <20250220225232.2138-1-mcassell411@gmail.com> Signed-off-by: Alejandro Colomar --- diff --git a/man/man2/mbind.2 b/man/man2/mbind.2 index fd1aca4ad..55a03a788 100644 --- a/man/man2/mbind.2 +++ b/man/man2/mbind.2 @@ -107,6 +107,7 @@ argument must specify one of .BR MPOL_INTERLEAVE , .BR MPOL_WEIGHTED_INTERLEAVE , .BR MPOL_PREFERRED , +.BR MPOL_PREFERRED_MANY , or .B MPOL_LOCAL (which are described in detail below). @@ -277,6 +278,11 @@ and arguments specify the empty set, then the memory is allocated on the node of the CPU that triggered the allocation. .TP +.BR MPOL_PREFERRED_MANY " (since Linux 5.15)" +.\" commit b27abaccf8e8b012f126da0c2a1ab32723ec8b9f +Specifies a set of nodes for allocation; see +.BR set_mempolicy (2) +.TP .BR MPOL_LOCAL " (since Linux 3.8)" .\" commit 479e2802d09f1e18a97262c4c6f8f17ae5884bd8 .\" commit f2a07f40dbc603c15f8b06e6ec7f768af67b424f diff --git a/man/man2/set_mempolicy.2 b/man/man2/set_mempolicy.2 index 2d0b1da19..19cae408a 100644 --- a/man/man2/set_mempolicy.2 +++ b/man/man2/set_mempolicy.2 @@ -65,6 +65,7 @@ argument must specify one of .BR MPOL_INTERLEAVE , .BR MPOL_WEIGHTED_INTERLEAVE , .BR MPOL_PREFERRED , +.BR MPOL_PREFERRED_MANY , or .B MPOL_LOCAL (which are described in detail below). @@ -234,6 +235,19 @@ arguments specify the empty set, then the policy specifies "local allocation" (like the system default policy discussed above). .TP +.BR MPOL_PREFERRED_MANY " (since Linux 5.15)" +.\" commit b27abaccf8e8b012f126da0c2a1ab32723ec8b9f +This mode specifies a preference for nodes +from which the kernel will try to allocate from. +This differs from +.B MPOL_PREFERRED +in that it accepts a set of nodes +versus a single node. +This policy is intended to benefit page allocations +where specific memory types +(i.e. non-volatile, high-bandwidth, or accelerator memory) +are of greater importance than node location. +.TP .BR MPOL_LOCAL " (since Linux 3.8)" .\" commit 479e2802d09f1e18a97262c4c6f8f17ae5884bd8 .\" commit f2a07f40dbc603c15f8b06e6ec7f768af67b424f