From fe1dcbc4f311c2e6c23b33c0fa8572461618ab3e Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Sat, 4 Feb 2006 23:27:54 -0800 Subject: [PATCH] jbd: fix transaction batching Ben points out that: When writing files out using O_SYNC, jbd's 1 jiffy delay results in a significant drop in throughput as the disk sits idle. The patch below results in a 4-5x performance improvement (from 6.5MB/s to ~24-30MB/s on my IDE test box) when writing out files using O_SYNC. So optimise the batching code by omitting it entirely if the process which is doing a sync write is the same as the one which did the most recent sync write. If that's true, we're unlikely to get any other processes joining the transaction. (Has been in -mm for ages - it took me a long time to get on to performance testing it) Numbers, on write-cache-disabled IDE: /usr/bin/time -p synctest -n 10 -uf -t 1 -p 1 dir-name Unpatched: 40 seconds Patched: 35 seconds Batching disabled: 35 seconds This is the problematic single-process-doing-fsync case. With multiple fsyncing processes the numbers are AFACIT unaltered by the patch. Aside: performance testing and instrumentation shows that the transaction batching almost doesn't help (testing with synctest -n 1 -uf -t 100 -p 10 dir-name on non-writeback-caching IDE). This is because by the time one process is running a synchronous commit, a bunch of other processes already have a transaction handle open, so they're all going to batch into the same transaction anyway. The batching seems to offer maybe 5-10% speedup with this workload, but I'm pretty sure it was more important than that when it was first developed 4-odd years ago... Cc: "Stephen C. Tweedie" Cc: Benjamin LaHaise Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/jbd.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/linux/jbd.h') diff --git a/include/linux/jbd.h b/include/linux/jbd.h index 558cb4c..751bb38 100644 --- a/include/linux/jbd.h +++ b/include/linux/jbd.h @@ -23,6 +23,7 @@ #define jfs_debug jbd_debug #else +#include #include #include #include @@ -618,6 +619,7 @@ struct transaction_s * @j_wbuf: array of buffer_heads for journal_commit_transaction * @j_wbufsize: maximum number of buffer_heads allowed in j_wbuf, the * number that will fit in j_blocksize + * @j_last_sync_writer: most recent pid which did a synchronous write * @j_private: An opaque pointer to fs-private information. */ @@ -807,6 +809,8 @@ struct journal_s struct buffer_head **j_wbuf; int j_wbufsize; + pid_t j_last_sync_writer; + /* * An opaque pointer to fs-private information. ext3 puts its * superblock pointer here -- cgit v1.1 From 1b8623545b42c03eb92e51b28c84acf4b8ba00a3 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 15 Dec 2005 01:07:03 -0500 Subject: [PATCH] remove bogus asm/bug.h includes. A bunch of asm/bug.h includes are both not needed (since it will get pulled anyway) and bogus (since they are done too early). Removed. Signed-off-by: Al Viro --- include/linux/jbd.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux/jbd.h') diff --git a/include/linux/jbd.h b/include/linux/jbd.h index 751bb38..0fe4aa8 100644 --- a/include/linux/jbd.h +++ b/include/linux/jbd.h @@ -239,7 +239,6 @@ typedef struct journal_superblock_s #include #include -#include #define JBD_ASSERTIONS #ifdef JBD_ASSERTIONS -- cgit v1.1