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Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug()

From Chris Mason <clm@fb.com>
Newsgroups linux.kernel
Subject Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug()
Date 2015-09-13 15:20 +0200
Message-ID <q8fmi-ga-13@gated-at.bofh.it> (permalink)
References (5 earlier) <q7FLQ-7Un-21@gated-at.bofh.it> <q7G5c-8gW-1@gated-at.bofh.it> <q825H-6zQ-1@gated-at.bofh.it> <q82p5-6WW-47@gated-at.bofh.it> <q82Ip-7jp-7@gated-at.bofh.it>
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On Sat, Sep 12, 2015 at 07:46:32PM -0400, Chris Mason wrote:
> I don't think the XFS numbers can be trusted too much since it was
> basically bottlenecked behind that single pegged CPU.  It was bouncing
> around and I couldn't quite track it down to a process name (or perf
> profile).

I'll do more runs Monday, but I was able to grab a perf profile of the
pegged XFS CPU.  It was just the writeback worker thread, and it
hit btrfs differently because we defer more of this stuff to endio
workers, effectively spreading it out over more CPUs.

With 4 mount points intead of 2, XFS goes from 140K files/sec to 250K.
Here's one of the profiles, but it bounced around a lot so I wouldn't
use this to actually tune anything:

   11.42%  kworker/u82:61  [kernel.kallsyms]  [k] _raw_spin_lock
            |
            ---_raw_spin_lock
               |
               |--83.43%-- xfs_extent_busy_trim
               |          xfs_alloc_compute_aligned
               |          |
               |          |--99.92%-- xfs_alloc_ag_vextent_near
               |          |          xfs_alloc_ag_vextent
               |          |          xfs_alloc_vextent
               |          |          xfs_bmap_btalloc
               |          |          xfs_bmap_alloc
               |          |          xfs_bmapi_write
               |          |          xfs_iomap_write_allocate
               |          |          xfs_map_blocks
               |          |          xfs_vm_writepage
               |          |          __writepage
               |          |          write_cache_pages
               |          |          generic_writepages
               |          |          xfs_vm_writepages
               |          |          do_writepages
               |          |          __writeback_single_inode
               |          |          writeback_sb_inodes
               |          |          __writeback_inodes_wb
               |          |          wb_writeback
               |          |          wb_do_writeback
               |          |          wb_workfn
               |          |          process_one_work
               |          |          worker_thread
               |          |          kthread
               |          |          ret_from_fork
               |           --0.08%-- [...]
               |

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Thread

[PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Chris Mason <clm@fb.com> - 2015-09-11 21:40 +0200
  Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-11 22:10 +0200
    Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-11 22:40 +0200
      Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Josef Bacik <jbacik@fb.com> - 2015-09-11 22:50 +0200
        Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-11 23:10 +0200
          Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-12 00:10 +0200
            Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Chris Mason <clm@fb.com> - 2015-09-12 01:20 +0200
              Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-12 01:40 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-12 03:00 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Chris Mason <clm@fb.com> - 2015-09-12 04:20 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-12 04:30 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Chris Mason <clm@fb.com> - 2015-09-13 01:10 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-13 01:30 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Chris Mason <clm@fb.com> - 2015-09-13 01:50 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Chris Mason <clm@fb.com> - 2015-09-13 15:20 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Dave Chinner <david@fromorbit.com> - 2015-09-14 01:00 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Dave Chinner <david@fromorbit.com> - 2015-09-14 01:20 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-14 22:10 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Jan Kara <jack@suse.cz> - 2015-09-16 22:00 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Chris Mason <clm@fb.com> - 2015-09-16 22:10 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Dave Chinner <david@fromorbit.com> - 2015-09-17 00:20 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Dave Chinner <david@fromorbit.com> - 2015-09-17 02:40 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-17 03:20 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Dave Chinner <david@fromorbit.com> - 2015-09-17 04:20 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-17 21:40 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Chris Mason <clm@fb.com> - 2015-09-18 00:50 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-18 01:10 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Chris Mason <clm@fb.com> - 2015-09-18 02:00 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Dave Chinner <david@fromorbit.com> - 2015-09-18 02:40 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-18 04:00 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Dave Chinner <david@fromorbit.com> - 2015-09-18 07:50 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-18 08:10 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-18 08:10 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Jens Axboe <axboe@fb.com> - 2015-09-18 16:30 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Chris Mason <clm@fb.com> - 2015-09-18 15:20 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Jens Axboe <axboe@fb.com> - 2015-09-18 16:30 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-18 17:40 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Peter Zijlstra <peterz@infradead.org> - 2015-09-18 18:10 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Peter Zijlstra <peterz@infradead.org> - 2015-09-18 18:10 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-18 18:20 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Dave Chinner <david@fromorbit.com> - 2015-09-19 01:20 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Jan Kara <jack@suse.cz> - 2015-09-21 11:30 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during  blk_finish_plug() Andrew Morton <akpm@linux-foundation.org> - 2015-09-21 22:30 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Dave Chinner <david@fromorbit.com> - 2015-09-18 01:10 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-18 01:20 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Chris Mason <clm@fb.com> - 2015-09-17 05:50 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Dave Chinner <david@fromorbit.com> - 2015-09-17 06:40 +0200
                Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Chris Mason <clm@fb.com> - 2015-09-17 14:20 +0200
          Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Chris Mason <clm@fb.com> - 2015-09-12 01:10 +0200
            Re: [PATCH] fs-writeback: drop wb->list_lock during blk_finish_plug() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-12 01:20 +0200

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