From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752950AbaJ0TGw (ORCPT ); Mon, 27 Oct 2014 15:06:52 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:52910 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752617AbaJ0TFD (ORCPT ); Mon, 27 Oct 2014 15:05:03 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Mikulas Patocka , Mike Snitzer , Kamal Mostafa Subject: [PATCH 3.13 075/105] dm bufio: when done scanning return from __scan immediately Date: Mon, 27 Oct 2014 11:56:50 -0700 Message-Id: <1414436240-13879-76-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1414436240-13879-1-git-send-email-kamal@canonical.com> References: <1414436240-13879-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11.10 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Mikulas Patocka commit 0e825862f3c04cee40e25f55680333728a4ffa9b upstream. When __scan frees the required number of buffer entries that the shrinker requested (nr_to_scan becomes zero) it must return. Before this fix the __scan code exited only the inner loop and continued in the outer loop -- which could result in reduced performance due to extra buffers being freed (e.g. unnecessarily evicted thinp metadata needing to be synchronously re-read into bufio's cache). Also, move dm_bufio_cond_resched to __scan's inner loop, so that iterating the bufio client's lru lists doesn't result in scheduling latency. Reported-by: Joe Thornber Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer Signed-off-by: Kamal Mostafa --- drivers/md/dm-bufio.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c index bb8d23d..a42efc7 100644 --- a/drivers/md/dm-bufio.c +++ b/drivers/md/dm-bufio.c @@ -1456,9 +1456,9 @@ static long __scan(struct dm_bufio_client *c, unsigned long nr_to_scan, list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list) { freed += __cleanup_old_buffer(b, gfp_mask, 0); if (!--nr_to_scan) - break; + return freed; + dm_bufio_cond_resched(); } - dm_bufio_cond_resched(); } return freed; } -- 1.9.1