Re: [patch] voluntary-preempt-2.6.9-rc3-mm3-T3

[Lee Revell]

On Tue, 2004-10-12 at 05:17, Ingo Molnar wrote:
> * Lee Revell <rlrevell@xxxxxxxxxxx> wrote:
> 
> > Just to recap, these are the three problem areas that still produce
> > latencies over 500 usec on my machine.
> > 
> > 	journal_clean_checkpoint_list
> 
> you might want to send this trace to Andrew too - the primary master of
> ext3 latency-breaking.
> 

OK, Andrew, here it is.  This is one of the last 2 or 3 code paths that
can still produce latencies > 200 usecs on a typical machine.

--

Also, I am still seeing some long latencies in the ext3 journaling code:

preemption latency trace v1.0.7 on 2.6.9-rc3-mm3-VP-T3
-------------------------------------------------------
 latency: 607 us, entries: 1087 (1087)   |   [VP:1 KP:1 SP:1 HP:1 #CPUS:1]
    -----------------
    | task: kjournald/687, uid:0 nice:0 policy:0 rt_prio:0
    -----------------
 => started at: journal_commit_transaction+0x75/0x2830
 => ended at:   __journal_clean_checkpoint_list+0xb2/0xf0
=======>
00000001 0.000ms (+0.003ms): journal_commit_transaction (kjournald)

Here is the loop:

00000002 0.003ms (+0.001ms): kfree (journal_commit_transaction)
00000001 0.004ms (+0.001ms): journal_refile_buffer (journal_commit_transaction)
00000003 0.006ms (+0.000ms): __journal_refile_buffer (journal_refile_buffer)
00000003 0.006ms (+0.001ms): __journal_unfile_buffer (journal_refile_buffer)
00000002 0.008ms (+0.000ms): journal_remove_journal_head (journal_refile_buffer)
00000003 0.008ms (+0.000ms): __journal_remove_journal_head (journal_remove_journal_head)
00000003 0.009ms (+0.000ms): __brelse (__journal_remove_journal_head)
00000003 0.010ms (+0.000ms): journal_free_journal_head (journal_remove_journal_head)
00000003 0.010ms (+0.001ms): kmem_cache_free (journal_free_journal_head)
00000001 0.011ms (+0.000ms): __brelse (journal_commit_transaction)

[end loop]

00000002 0.012ms (+0.000ms): kfree (journal_commit_transaction)
00000001 0.013ms (+0.000ms): journal_refile_buffer (journal_commit_transaction)

Lee

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