On Fri, 03 Jun 2011, Andrew Hastings wrote: > Hello, Eric! > > On 05/26/2011 12:13 PM, Eric B Munson wrote: > >diff --git a/HOWTO b/HOWTO > >index 3c1f124..b018543 100644 > >--- a/HOWTO > >+++ b/HOWTO > >@@ -2,7 +2,7 @@ libhugetlbfs HOWTO > > ================== > > > > Author: David Gibson<d...@au1.ibm.com>, Adam Litke<a...@us.ibm.com>, and > > others > >-Last updated: February 1st, 2011 > >+Last updated: May 25th, 2011 > > > > Introduction > > ============ > >@@ -264,6 +264,11 @@ environment variables: > > To use a specific huge page size: > > HUGETLB_MORECORE=<pagesize> > > > >+ To use Transparent Huge Pages (THP): > >+ HUGETLB_MORECORE=thp > >+ > >+Note: This option requires a kernel that supports Transparent Huge Pages > >+ > > Usually it's preferable to set these environment variables on the > > command line of the program you wish to run, rather than using > > "export", because you'll only want to enable the hugepage malloc() for > >@@ -599,6 +604,10 @@ libhugetlbfs: > > HUGETLB_NO_PREFAULT > > Explained in "Using hugepages for malloc() > > (morecore)" > >+ HUGETLB_THP_MADVISE > >+ When using thp for HUGETLB_MORECORE, this signals that > >+ allocations for the heap should use madvise(MADV_HUGEPAGE) to > >+ mark them as appropriate for collapsing by khugepaged > > Probably just idle curiosity, but why would someone want to set > HUGETLB_MORECORE=thp and not set HUGETLB_THP_MADVISE at the same > time? > > Might it make sense for HUGETLB_MORECORE=thp to automatically turn > on the madvise(MADV_HUGEPAGE)? If necessary, a separate env. var. > could disable the automatic madvise.
It is possible to use THP without being madvise'd, infact if I read the transhuge documentation correctly, the madvise is only useful when system-wide transparent huge pages are not enabled (the sysctl is set to madvise). > > > >@@ -220,7 +229,8 @@ void hugetlbfs_setup_morecore(void) > > * This can be set explicitly by setting HUGETLB_MORECORE to a valid > > * page size string or by setting HUGETLB_DEFAULT_PAGE_SIZE. > > */ > >- if (strncasecmp(__hugetlb_opts.morecore, "y", 1) == 0) > >+ if ((strncasecmp(__hugetlb_opts.morecore, "y", 1) == 0) || > >+ __hugetlb_opts.thp_morecore) > > hpage_size = gethugepagesize(); > > else > > hpage_size = parse_page_size(__hugetlb_opts.morecore); > > thp_morecore should probably use kernel_default_hugepage_size() > instead of gethugepagesize(). gethugepagesize() will use > HUGETLB_DEFAULT_PAGE_SIZE if set. Thanks, I will make this change for the next revision. > > -Andrew Hastings > Cray Inc. >
signature.asc
Description: Digital signature
------------------------------------------------------------------------------ EditLive Enterprise is the world's most technically advanced content authoring tool. Experience the power of Track Changes, Inline Image Editing and ensure content is compliant with Accessibility Checking. http://p.sf.net/sfu/ephox-dev2dev
_______________________________________________ Libhugetlbfs-devel mailing list Libhugetlbfs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libhugetlbfs-devel
