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madvise.2: Reorder MAD_FREE entry 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
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Michael Kerrisk 2016-02-06 12:53:01 +01:00
parent cbb9ef3061
commit 9ec1369898
1 changed files with 17 additions and 19 deletions
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@ -143,25 +143,6 @@ flag are special memory areas that are not managed
by the virtual memory subsystem.
Such pages are typically created by device drivers that
map the pages into user space.)
.TP
.B MADV_FREE " (since Linux 4.5)"
Application is finished with the given range, so kernel can free
resources associated with it but the freeing could be delayed until
memory pressure happens or canceld by write operation by user.
After a successful MADV_FREE operation, user shouldn't expect kernel
keeps stale data on the page. However, subsequent write of pages
in the range will succeed and then kernel cannot free those dirtied pages
so user can always see just written data. If there was no subsequent
write, kernel can free those clean pages any time. In such case,
user can see zero-fill-on-demand pages.
Note that, it works only with private anonymous pages (see
.BR mmap (2)).
On swapless system, freeing pages in given range happens instantly
regardless of memory pressure.
.\"
.\" ======================================================================
.\"
@ -380,6 +361,23 @@ file (see
.BR MADV_DODUMP " (since Linux 3.4)"
Undo the effect of an earlier
.BR MADV_DONTDUMP .
.TP
.B MADV_FREE " (since Linux 4.5)"
Application is finished with the given range, so kernel can free
resources associated with it but the freeing could be delayed until
memory pressure happens or canceld by write operation by user.
After a successful MADV_FREE operation, user shouldn't expect kernel
keeps stale data on the page. However, subsequent write of pages
in the range will succeed and then kernel cannot free those dirtied pages
so user can always see just written data. If there was no subsequent
write, kernel can free those clean pages any time. In such case,
user can see zero-fill-on-demand pages.
Note that, it works only with private anonymous pages (see
.BR mmap (2)).
On swapless system, freeing pages in given range happens instantly
regardless of memory pressure.
.SH RETURN VALUE
On success,
.BR madvise ()