On Tue, 2008-10-28 at 13:54 +0000, Andy Whitcroft wrote:
> We use the kernel default page size all over the place. We use it
> approximatly 6 times when setting the boundaries on a single pool.
> Currently every place looks this value up in /proc/meminfo which is
> very costly.
>
> As this value is essentially static per boot we can cache this value.
> Create a new routine kernel_default_hugepage_size() which looks this
> up and caches the result.
>
> Signed-off-by: Andy Whitcroft <[EMAIL PROTECTED]>
> Acked-by: Eric B Munson <[EMAIL PROTECTED]>
> Acked-by: Mel Gorman <[EMAIL PROTECTED]>
Acked-by: Adam Litke <[EMAIL PROTECTED]>
> ---
> hugeutils.c | 33 +++++++++++++++++++++------------
> libhugetlbfs_privutils.h | 3 +++
> shm.c | 2 +-
> 3 files changed, 25 insertions(+), 13 deletions(-)
>
> diff --git a/hugeutils.c b/hugeutils.c
> index ba8f46d..736d07d 100644
> --- a/hugeutils.c
> +++ b/hugeutils.c
> @@ -55,10 +55,24 @@ static struct hpage_size hpage_sizes[MAX_HPAGE_SIZES];
> static int nr_hpage_sizes;
> static int hpage_sizes_default_idx = -1;
>
> +static int default_size;
> +
> /********************************************************************/
> /* Internal functions */
> /********************************************************************/
>
> +/*
> + * Lookup the kernel default page size.
> + */
> +long kernel_default_hugepage_size()
> +{
> + if (default_size == 0) {
> + default_size = file_read_ulong(MEMINFO, "Hugepagesize:");
> + default_size = size_to_smaller_unit(default_size); /* kB to B */
> + }
> + return default_size;
> +}
> +
> #define BUF_SZ 256
> #define MEMINFO_SIZE 2048
>
> @@ -240,8 +254,7 @@ static int select_pool_counter(unsigned int counter,
> unsigned long pagesize,
> * between libhugetlbfs and the test suite. For now we will just
> * read /proc/meminfo.
> */
> - default_size = file_read_ulong(MEMINFO, "Hugepagesize:");
> - default_size = size_to_smaller_unit(default_size); /* kB to B */
> + default_size = kernel_default_hugepage_size();
> if (default_size < 0) {
> ERROR("Cannot determine the default page size\n");
> return -1;
> @@ -290,8 +303,7 @@ static void probe_default_hpage_size(void)
> if (env && strlen(env) > 0)
> size = parse_page_size(env);
> else {
> - size = file_read_ulong(MEMINFO, "Hugepagesize:");
> - size *= 1024; /* convert from kB to B */
> + size = kernel_default_hugepage_size();
> }
>
> if (size >= 0) {
> @@ -506,8 +518,7 @@ int hpool_sizes(struct hpage_pool *pools, int pcnt)
> DIR *dir;
> struct dirent *entry;
>
> - default_size = size_to_smaller_unit(file_read_ulong(MEMINFO,
> - "Hugepagesize:"));
> + default_size = kernel_default_hugepage_size();
> if (default_size >= 0 && which < pcnt)
> if (get_pool_size(default_size, &pools[which])) {
> pools[which].is_default = 1;
> @@ -543,8 +554,7 @@ int hpool_sizes(struct hpage_pool *pools, int pcnt)
> */
> int kernel_has_hugepages(void)
> {
> - long default_size = file_read_ulong(MEMINFO, "Hugepagesize:");
> - default_size = size_to_smaller_unit(default_size);
> + long default_size = kernel_default_hugepage_size();
> if (default_size < 0)
> return 0;
>
> @@ -557,8 +567,7 @@ int kernel_has_hugepages(void)
> */
> int kernel_has_overcommit(void)
> {
> - long default_size = file_read_ulong(MEMINFO, "Hugepagesize:");
> - default_size = size_to_smaller_unit(default_size);
> + long default_size = kernel_default_hugepage_size();
> if (default_size < 0)
> return 0;
>
> @@ -616,8 +625,8 @@ int gethugepagesizes(long pagesizes[], int n_elem)
>
> errno = 0;
>
> - /* Get the system default size from /proc/meminfo */
> - default_size = read_meminfo("Hugepagesize:") * 1024;
> + /* Get the system default size. */
> + default_size = kernel_default_hugepage_size();
> if (default_size < 0)
> return 0;
>
> diff --git a/libhugetlbfs_privutils.h b/libhugetlbfs_privutils.h
> index 4e01aac..c31d526 100644
> --- a/libhugetlbfs_privutils.h
> +++ b/libhugetlbfs_privutils.h
> @@ -61,6 +61,9 @@ int kernel_has_overcommit(void);
> #define read_meminfo __pu_read_meminfo
> long read_meminfo(const char *tag);
>
> +#define kernel_default_hugepage_size __pu_kernel_default_hugepage_size
> +long kernel_default_hugepage_size(void);
> +
> /* Kernel feature testing */
> /* This enum defines the bits in a feature bitmask */
> enum {
> diff --git a/shm.c b/shm.c
> index 8a56725..ac3b52a 100644
> --- a/shm.c
> +++ b/shm.c
> @@ -60,7 +60,7 @@ int shmget(key_t key, size_t size, int shmflg)
> * Use /proc/meminfo because shm always uses the system
> * default huge page size.
> */
> - long hpage_size = read_meminfo("Hugepagesize:") * 1024;
> + long hpage_size = kernel_default_hugepage_size();
> aligned_size = ALIGN(size, hpage_size);
> if (size != aligned_size) {
> DEBUG("hugetlb_shmem: size growth align %zd -> %zd\n",
--
Adam Litke - (agl at us.ibm.com)
IBM Linux Technology Center
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