From 0310fa216decc3ecfab41f327638fa48a81f3735 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Tue, 5 Aug 2008 15:54:14 +1000 Subject: [PATCH] Allow raid10 resync to happening in larger chunks. MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The raid10 resync/recovery code currently limits the amount of in-flight resync IO to 2Meg. This was copied from raid1 where it seems quite adequate. However for raid10, some layouts require a bit of seeking to perform a resync, and allowing a larger buffer size means that the seeking can be significantly reduced. There is probably no real need to limit the amount of in-flight IO at all. Any shortage of memory will naturally reduce the amount of buffer space available down to a set minimum, and any concurrent normal IO will quickly cause resync IO to back off. The only problem would be that normal IO has to wait for all resync IO to finish, so a very large amount of resync IO could cause unpleasant latency when normal IO starts up. So: increase RESYNC_DEPTH to allow 32Meg of buffer (if memory is available) which seems to be a good amount. Also reduce the amount of memory reserved as there is no need to keep 2Meg just for resync if memory is tight. Thanks to Keld for the suggestion. Cc: Keld Jørn Simonsen Signed-off-by: NeilBrown --- drivers/md/raid10.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index d41bebb6da..e34cd0e624 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -76,11 +76,13 @@ static void r10bio_pool_free(void *r10_bio, void *data) kfree(r10_bio); } +/* Maximum size of each resync request */ #define RESYNC_BLOCK_SIZE (64*1024) -//#define RESYNC_BLOCK_SIZE PAGE_SIZE -#define RESYNC_SECTORS (RESYNC_BLOCK_SIZE >> 9) #define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE) -#define RESYNC_WINDOW (2048*1024) +/* amount of memory to reserve for resync requests */ +#define RESYNC_WINDOW (1024*1024) +/* maximum number of concurrent requests, memory permitting */ +#define RESYNC_DEPTH (32*1024*1024/RESYNC_BLOCK_SIZE) /* * When performing a resync, we need to read and compare, so @@ -690,7 +692,6 @@ static int flush_pending_writes(conf_t *conf) * there is no normal IO happeing. It must arrange to call * lower_barrier when the particular background IO completes. */ -#define RESYNC_DEPTH 32 static void raise_barrier(conf_t *conf, int force) { -- 2.39.5