Hello Doug, On Wed, Jul 27, 2011 at 10:14 PM, Doug Goldstein <cardoe@xxxxxxxxxx> wrote: > Document the MADV_HUGEPAGE and MADV_NOHUGEPAGE flags added to the > madvise() syscall in Linux kernels 2.6.38 and newer. Thanks. I've applied this for man-pages-3.34. Andrea, is there anything you think necessary to add/change? Cheers, Michael > Signed-off-by: Doug Goldstein <cardoe@xxxxxxxxxx> > --- > man2/madvise.2 | 34 ++++++++++++++++++++++++++++++++++ > 1 files changed, 34 insertions(+), 0 deletions(-) > > diff --git a/man2/madvise.2 b/man2/madvise.2 > index 6a449c5..e099e94 100644 > --- a/man2/madvise.2 > +++ b/man2/madvise.2 > @@ -209,6 +209,40 @@ KSM unmerges whatever pages it had merged in the > address range specified by > .IR addr > and > .IR length . > +.TP > +.BR MADV_HUGEPAGE " (since Linux 2.6.38)" > +Enables Transparent Huge Pages (THP) for pages in the range specified by > +.I addr > +and > +.IR length . > +Currently Transparent Huge Pages only work with private anonymous pages (see > +.BR mmap (2)). > +The kernel will regularly scan the areas marked as huge page candidates > +to replace them with huge pages. > +The kernel will also allocate huge pages directly when the region is > +naturally aligned to the huge page size. (see > +.BR posix_memalign (2)). > +This feature is primarily aimmed at applications that use large mappings of > +data and access large regions of that memory at a time (e.g. virtualization > +systems such as qemu). > +It can very easily waste memory (e.g. a 2MB mapping that only ever accesses > +1 byte will result in 2MB of wired memory instead of one 4KB page). > +See the kernel source file > +.I Documentation/vm/transhuge.txt > +for more details. > +The > +.BR MADV_HUGEPAGE > +and > +.BR MADV_NOHUGEPAGE > +operations are only available if the kernel was configured with > +.BR CONFIG_TRANSPARENT_HUGEPAGE. > +.TP > +.BR MADV_NOHUGEPAGE " (since Linux 2.6.38)" > +Ensures that memory in the address range specified by > +.IR addr > +and > +.IR length > +will not be collapsed into huge pages. > .SH "RETURN VALUE" > On success > .BR madvise () > -- > 1.7.6 > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Author of "The Linux Programming Interface"; http://man7.org/tlpi/ -- 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
