Messages in this thread | | | Subject | Re: -rt dbench scalabiltiy issue | From | john stultz <> | Date | Tue, 24 Nov 2009 18:16:17 -0800 |
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On Mon, 2009-11-23 at 10:06 +0100, Nick Piggin wrote: > BTW. Have you tested like ext4, xfs and btrfs cases? I don't think ext3 > is likely to see a huge amount of scalability work, and so it will be > good to give an early heads up to the more active projects...
Yea, I need to give those a shot. I also generated the same numbers as before with ext2 (all the raw numbers are in dbench-scalability dir):
http://sr71.net/~jstultz/dbench-scalability/graphs/ext2-scalability.png
Again, its similar to ext3, in that all the -rt variants are hitting some contention issues. But I was a little surprised to see 2.6.32-rc7-nick below 2.6.32-rc7 there, so generated perf data there as well:
http://sr71.net/~jstultz/dbench-scalability/perflogs/2.6.32-rc7-nick.ext2.perflog
31.91% dbench [kernel] [k] _spin_lock | |--44.17%-- dput | | | |--50.39%-- __link_path_walk | | | | | |--99.88%-- path_walk | | | | | | | |--96.18%-- do_path_lookup | | | | | | | | | |--51.49%-- user_path_at | | | | | | | | | | | |--96.84%-- vfs_fstatat | | | | | | vfs_stat | | | | | | sys_newstat | | | | | | system_call_fastpath | | | | | | _xstat | | | | | | | | | | | --3.16%-- do_utimes | | | | | sys_utime | | | | | system_call_fastpath | | | | | __GI_utime | | | | | | | | | |--43.18%-- do_filp_open | | | | | do_sys_open | | | | | sys_open | | | | | system_call_fastpath | | | | | __GI___open ...
|--39.98%-- path_get | | | |--51.19%-- path_init | | | | | |--96.40%-- do_path_lookup | | | | | | | |--55.12%-- user_path_at | | | | | | | | | |--91.47%-- vfs_fstatat | | | | | vfs_stat | | | | | sys_newstat | | | | | system_call_fastpath | | | | | _xstat | | | | | | | | | | | --100.00%-- 0x7478742e746e65 | | | | |
So I'm a little confused here. Why is dput/path_get showing up in ext2 when it all but disappeared with ramfs? Does ramfs have some sort of vfs_stat shortcut that avoids whatever is catching us here?
thanks -john
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