Hi, * On Sat, Sep 22, 2012 at 08:42:50PM +0800, Fengguang Wu wrote: >it.rprabhu@wnohang.net> >User-Agent: Mutt/1.5.21 (2010-09-15) >X-Date: Sat Sep 22 18:12:50 IST 2012 > >On Sat, Sep 22, 2012 at 04:03:13PM +0530, raghu.prabhu13@gmail.com wrote: >> From: Raghavendra D Prabhu >> >> page_cache_sync_readahead checks for ra->ra_pages again, so moving the check >> after VM_SequentialReadHint. > >Well it depends on what case you are optimizing for. I suspect there >are much more tmpfs users than VM_SequentialReadHint users. So this >change is actually not desirable wrt the more widely used cases. shm/tmpfs doesn't use this function for fault. They have shmem_fault for that. So, that shouldn't matter here. Agree? > >Thanks, >Fengguang > >> Signed-off-by: Raghavendra D Prabhu >> --- >> mm/filemap.c | 5 +++-- >> 1 file changed, 3 insertions(+), 2 deletions(-) >> >> diff --git a/mm/filemap.c b/mm/filemap.c >> index 3843445..606a648 100644 >> --- a/mm/filemap.c >> +++ b/mm/filemap.c >> @@ -1523,8 +1523,6 @@ static void do_sync_mmap_readahead(struct vm_area_struct *vma, >> /* If we don't want any read-ahead, don't bother */ >> if (VM_RandomReadHint(vma)) >> return; >> - if (!ra->ra_pages) >> - return; >> >> if (VM_SequentialReadHint(vma)) { >> page_cache_sync_readahead(mapping, ra, file, offset, >> @@ -1532,6 +1530,9 @@ static void do_sync_mmap_readahead(struct vm_area_struct *vma, >> return; >> } >> >> + if (!ra->ra_pages) >> + return; >> + >> /* Avoid banging the cache line if not needed */ >> if (ra->mmap_miss < MMAP_LOTSAMISS * 10) >> ra->mmap_miss++; >> -- >> 1.7.12.1 >> >> -- >> To unsubscribe, send a message with 'unsubscribe linux-mm' in >> the body to majordomo@kvack.org. For more info on Linux MM, >> see Regards, -- Raghavendra Prabhu GPG Id : 0xD72BE977 Fingerprint: B93F EBCB 8E05 7039 CD3C A4B8 A616 DCA1 D72B E977 www: wnohang.net