Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753825AbcDYHvP (ORCPT ); Mon, 25 Apr 2016 03:51:15 -0400 Received: from ns.lynxeye.de ([87.118.118.114]:58387 "EHLO lynxeye.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753701AbcDYHvO (ORCPT ); Mon, 25 Apr 2016 03:51:14 -0400 From: Lucas Stach To: Dave Chinner Cc: xfs@oss.sgi.com, linux-kernel@vger.kernel.org Subject: [PATCH] xfs: idle aild if the AIL is pushed up to the target LSN Date: Mon, 25 Apr 2016 09:42:43 +0200 Message-Id: <1461570163-4083-1-git-send-email-dev@lynxeye.de> X-Mailer: git-send-email 2.5.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2134 Lines: 56 The current logic only idles aild if the AIL is empty, rescheduling the worker with a timeout of 50ms otherwise. If the target LSN isn't moved forward, the worker will not make any progress as it only pushes the AIL up to the target LSN, leading to the empty AIL condition to only be met after the log worker pushed the complete AIL. As the log worker runs on the scale of minutes, this leaves aild in the "no progress, 50ms timeout" state for extended periods of time, causing many unecessary wakeups. Fix this by idling aild as soon as the AIL is pushed up to the target LSN. All code paths that move the target LSN forward already ensure that aild is woken up again when needed. Signed-off-by: Lucas Stach --- I'm pretty sure that the above deduction is correct, but as this my first real encounter with the XFS code base, someone with a bit more knowledge than me should give this some thought. --- fs/xfs/xfs_trans_ail.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c index d6c9c3e..7eca852 100644 --- a/fs/xfs/xfs_trans_ail.c +++ b/fs/xfs/xfs_trans_ail.c @@ -495,6 +495,7 @@ xfsaild( { struct xfs_ail *ailp = data; long tout = 0; /* milliseconds */ + struct xfs_log_item *lip; current->flags |= PF_MEMALLOC; set_freezable(); @@ -508,7 +509,8 @@ xfsaild( spin_lock(&ailp->xa_lock); /* - * Idle if the AIL is empty and we are not racing with a target + * Idle if the AIL is empty or pushed up to the requested + * target LSN and we are not racing with a target * update. We check the AIL after we set the task to a sleep * state to guarantee that we either catch an xa_target update * or that a wake_up resets the state to TASK_RUNNING. @@ -517,7 +519,8 @@ xfsaild( * The barrier matches the xa_target update in xfs_ail_push(). */ smp_rmb(); - if (!xfs_ail_min(ailp) && + lip = xfs_ail_min(ailp); + if ((!lip || XFS_LSN_CMP(lip->li_lsn, ailp->xa_target) >= 0) && ailp->xa_target == ailp->xa_target_prev) { spin_unlock(&ailp->xa_lock); freezable_schedule(); -- 2.5.5