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From: Stefan Priebe - Profihost AG <s.priebe@profihost.ag>
To: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: Christoph Hellwig <hch@infradead.org>, Tejun Heo <tj@kernel.org>,
	xfs@oss.sgi.com
Subject: Re: [PATCH 3/4] xfs: revert to using a kthread for AIL pushing
Date: Mon, 10 Oct 2011 08:06:25 +0200	[thread overview]
Message-ID: <4E928B61.8080107@profihost.ag> (raw)
In-Reply-To: <20111010055546.GA1641@x4.trippels.de>

Am 10.10.2011 07:55, schrieb Markus Trippelsdorf:
> Wouldn't it be possible to verify that the problem also goes away with
> this simple one liner?
>
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 2366c54..daf30c9 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -1654,7 +1654,7 @@ xfs_init_workqueues(void)
>   	if (!xfs_syncd_wq)
>   		goto out;
>
> -	xfs_ail_wq = alloc_workqueue("xfsail", WQ_CPU_INTENSIVE, 8);
> +	xfs_ail_wq = alloc_workqueue("xfsail", WQ_HIGHPRI | WQ_CPU_INTENSIVE, 8);
>   	if (!xfs_ail_wq)
>   		goto out_destroy_syncd;
>
>  From Documentation/workqueue.txt:
>
>    WQ_HIGHPRI | WQ_CPU_INTENSIVE
>
> 	This combination makes the wq avoid interaction with
> 	concurrency management completely and behave as a simple
> 	per-CPU execution context provider.  Work items queued on a
> 	highpri CPU-intensive wq start execution as soon as resources
> 	are available and don't affect execution of other work items.
>
> So this should be identical to reverting back to the kthread. No?
> CCing Tejun, maybe he can comment on this?

We already tested this patch and it still fails / deadlocks:

diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index a1a881e..6377f51 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -1669,7 +1669,7 @@ xfs_init_workqueues(void)
  	if (!xfs_syncd_wq)
  		goto out;

-	xfs_ail_wq = alloc_workqueue("xfsail", WQ_CPU_INTENSIVE, 8);
+	xfs_ail_wq = alloc_workqueue("xfsail", WQ_MEM_RECLAIM | WQ_HIGHPRI, 512);
  	if (!xfs_ail_wq)
  		goto out_destroy_syncd;

diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c
index 953b142..638ea8b 100644
--- a/fs/xfs/xfs_trans_ail.c
+++ b/fs/xfs/xfs_trans_ail.c
@@ -600,7 +600,7 @@ out_done:
  	}

  	/* There is more to do, requeue us.  */
-	queue_delayed_work(xfs_syncd_wq, &ailp->xa_work,
+	queue_delayed_work(xfs_ail_wq, &ailp->xa_work,
  					msecs_to_jiffies(tout));
  }

@@ -637,7 +637,7 @@ xfs_ail_push(
  	smp_wmb();
  	xfs_trans_ail_copy_lsn(ailp, &ailp->xa_target, &threshold_lsn);
  	if (!test_and_set_bit(XFS_AIL_PUSHING_BIT, &ailp->xa_flags))
-		queue_delayed_work(xfs_syncd_wq, &ailp->xa_work, 0);
+		queue_delayed_work(xfs_ail_wq, &ailp->xa_work, 0);
  }

  /*


Stefan

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  reply	other threads:[~2011-10-10  6:06 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-10-06 18:32 [PATCH 0/4] fix AIL pushing under heavy concurrent metadata loads Christoph Hellwig
2011-10-06 18:32 ` [PATCH 1/4] xfs: do not update xa_last_pushed_lsn for locked items Christoph Hellwig
2011-10-07 22:18   ` Alex Elder
2011-10-10  1:37   ` Dave Chinner
2011-10-06 18:32 ` [PATCH 2/4] xfs: force the log if we encounter pinned buffers in .iop_pushbuf Christoph Hellwig
2011-10-07 22:18   ` Alex Elder
2011-10-10  1:39   ` Dave Chinner
2011-10-06 18:33 ` [PATCH 3/4] xfs: revert to using a kthread for AIL pushing Christoph Hellwig
2011-10-07 22:18   ` Alex Elder
2011-10-10  1:45   ` Dave Chinner
2011-10-10  5:55     ` Markus Trippelsdorf
2011-10-10  6:06       ` Stefan Priebe - Profihost AG [this message]
2011-10-10 13:26       ` Christoph Hellwig
2011-10-10 18:37         ` Tejun Heo
2011-10-19 11:16       ` Stefan Priebe - Profihost AG
2011-10-19 11:34         ` Christoph Hellwig
2011-10-19 13:10           ` Stefan Priebe - Profihost AG
2011-10-06 18:33 ` [PATCH 4/4] xfs: add AIL pushing tracepoints Christoph Hellwig
2011-10-07 22:18   ` Alex Elder
2011-10-10  1:45   ` Dave Chinner
  -- strict thread matches above, loose matches on Subject: below --
2011-10-11 15:14 [PATCH 0/4] fix AIL pushing under heavy concurrent metadata loads V2 Christoph Hellwig
2011-10-11 15:14 ` [PATCH 3/4] xfs: revert to using a kthread for AIL pushing Christoph Hellwig

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