From 6d4831c283530a5f2c6bd8172c13efa236eb149d Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Wed, 27 Apr 2011 15:26:41 -0700 Subject: [PATCH] vfs: avoid large kmalloc()s for the fdtable Azurit reports large increases in system time after 2.6.36 when running Apache. It was bisected down to a892e2d7dcdfa6c76e6 ("vfs: use kmalloc() to allocate fdmem if possible"). That patch caused the vfs to use kmalloc() for very large allocations and this is causing excessive work (and presumably excessive reclaim) within the page allocator. Fix it by falling back to vmalloc() earlier - when the allocation attempt would have been considered "costly" by reclaim. Reported-by: azurIt Tested-by: azurIt Acked-by: Changli Gao Cc: Americo Wang Cc: Jiri Slaby Acked-by: Eric Dumazet Cc: Mel Gorman Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/file.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/fs/file.c b/fs/file.c index 0be344755c02..4c6992d8f3ba 100644 --- a/fs/file.c +++ b/fs/file.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include #include @@ -39,14 +40,17 @@ int sysctl_nr_open_max = 1024 * 1024; /* raised later */ */ static DEFINE_PER_CPU(struct fdtable_defer, fdtable_defer_list); -static inline void *alloc_fdmem(unsigned int size) +static void *alloc_fdmem(unsigned int size) { - void *data; - - data = kmalloc(size, GFP_KERNEL|__GFP_NOWARN); - if (data != NULL) - return data; - + /* + * Very large allocations can stress page reclaim, so fall back to + * vmalloc() if the allocation size will be considered "large" by the VM. + */ + if (size <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER)) { + void *data = kmalloc(size, GFP_KERNEL|__GFP_NOWARN); + if (data != NULL) + return data; + } return vmalloc(size); } -- 2.30.2