Messages in this thread |  | | From | kumon@flab ... | Date | Thu, 26 Oct 2000 23:05:01 +0900 | Subject | Re: Strange performance behavior of 2.4.0-test9 |
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kumon@flab.fujitsu.co.jp writes: > Rik van Riel writes: > > On Wed, 25 Oct 2000 kumon@flab.fujitsu.co.jp wrote: > > > I found very odd performance behavior of 2.4.0-test9 on a large SMP > > > server, and I want some clues to investigate it. > > > > > > 1) At the 8 cpu configuration, test9 shows extremely inferior > > > performance. > > > 2) on test8, 8-cpu configuration shows about 2/3 performance of 4-cpu. > > ^^^^^ test9 ??
IMHO, the modification of file-system code causes the weird performance.
Most of processes are slept at: posix_lock_file()->locks_block_on()->interruptible_sleep_on_locks()
We revert two of test9 files (fs/fcntl.c fs/flock.c), to the previous version, the performance problem disappeared and it becomes to the same level as test8.
To narrow the problem, we measured performance of 3 configuration: 1) test9 with test8 fs/fcntl.c, test8 fs/flock.c 2) test9 with test8 fs/fcntl.c 3) test9 with test8 fs/flock.c
Only 3) shows the problem, so the main problem reside in fcntl.c (not in flock.c).
So it seems: the web-server, apache-1.3.9 in the redhat-6.1, issues lots of fcntl to the file and those fcntls collide each other, and the processes are blocked.
What has happend to fcntl.c?
-- Computer Systems Laboratory, Fujitsu Labs. kumon@flab.fujitsu.co.jp - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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