On Wed, May 13, 2009 at 10:07:50AM +0100, Eric B Munson wrote:
> Prefaulting should be disabled when the kernel supports private reservations.
> Currently this check is part of the morecore_setup function and is only made
> if HUGETLB_MORECORE is 'yes'. This is a problem for users of
> get_hugepage_region because prefaulting will slow allocation down
> significantly.
Slow down allocation significantly *and* screw with NUMA placement
policies where we want to do demand faulting.
> This patch moves the check for private reservations into s separate function
> that is called during hugetlb_setup.
>
> Signed-off-by: Eric B Munson <ebmun...@us.ibm.com>
Looks good.
Acked-by: Mel Gorman <m...@csn.ul.ie>
> ---
> hugeutils.c | 14 ++++++++++++++
> init.c | 1 +
> libhugetlbfs_internal.h | 2 ++
> morecore.c | 11 -----------
> 4 files changed, 17 insertions(+), 11 deletions(-)
>
> diff --git a/hugeutils.c b/hugeutils.c
> index 86dd120..d6f8940 100644
> --- a/hugeutils.c
> +++ b/hugeutils.c
> @@ -302,6 +302,20 @@ void hugetlbfs_setup_env()
> __hugetlb_opts.shm_enabled = 1;
> }
>
> +void hugetlbfs_check_priv_resv()
> +{
> + /*
> + * If the kernel supports MAP_PRIVATE reservations, we can skip
> + * prefaulting the huge pages we allocate since the kernel
> + * guarantees them. This can help NUMA performance quite a bit.
> + */
> + if (hugetlbfs_test_feature(HUGETLB_FEATURE_PRIVATE_RESV)) {
> + INFO("Kernel has MAP_PRIVATE reservations. Disabling "
> + "heap prefaulting.\n");
> + __hugetlbfs_prefault = 0;
> + }
> +}
> +
> /*
> * Pool counters are typically exposed in sysfs in modern kernels, the
> * counters for the default page size are exposed in procfs in all kernels
> diff --git a/init.c b/init.c
> index 794e03c..e95cb5c 100644
> --- a/init.c
> +++ b/init.c
> @@ -25,6 +25,7 @@ static void __attribute__ ((constructor))
> setup_libhugetlbfs(void)
> hugetlbfs_setup_debug();
> setup_mounts();
> setup_features();
> + hugetlbfs_check_priv_resv();
> #ifndef NO_ELFLINK
> hugetlbfs_setup_elflink();
> #endif
> diff --git a/libhugetlbfs_internal.h b/libhugetlbfs_internal.h
> index b3c3a38..05c22e0 100644
> --- a/libhugetlbfs_internal.h
> +++ b/libhugetlbfs_internal.h
> @@ -98,6 +98,8 @@ extern void hugetlbfs_setup_debug();
> extern void setup_mounts();
> #define setup_features __lh_setup_features
> extern void setup_features();
> +#define hugetlbfs_check_priv_resv __lh_hugetlbfs_check_priv_resv
> +extern void hugetlbfs_check_priv_resv();
> #define __hugetlbfs_hostname __lh___hugetlbfs_hostname
> extern char __hugetlbfs_hostname[];
> #define hugetlbfs_prefault __lh_hugetlbfs_prefault
> diff --git a/morecore.c b/morecore.c
> index 56acf44..232e04a 100644
> --- a/morecore.c
> +++ b/morecore.c
> @@ -227,17 +227,6 @@ void hugetlbfs_setup_morecore(void)
> return;
> }
>
> - /*
> - * If the kernel supports MAP_PRIVATE reservations, we can skip
> - * prefaulting the huge pages we allocate for the heap since the
> - * kernel guarantees them. This can help NUMA performance quite a bit.
> - */
> - if (hugetlbfs_test_feature(HUGETLB_FEATURE_PRIVATE_RESV)) {
> - INFO("Kernel has MAP_PRIVATE reservations. Disabling "
> - "heap prefaulting.\n");
> - __hugetlbfs_prefault = 0;
> - }
> -
> if (hpage_size <= 0) {
> if (errno == ENOSYS)
> WARNING("Hugepages unavailable\n");
> --
> 1.6.1.2
>
>
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>
--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
------------------------------------------------------------------------------
The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your
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Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700
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processing features enabled. http://p.sf.net/sfu/kodak-com
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