From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id o3K2ebI7256108 for ; Mon, 19 Apr 2010 21:40:38 -0500 Received: from mail.internode.on.net (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 7135B12D1707 for ; Mon, 19 Apr 2010 19:42:34 -0700 (PDT) Received: from mail.internode.on.net (bld-mail17.adl2.internode.on.net [150.101.137.102]) by cuda.sgi.com with ESMTP id Tka1FvBqD6IYqjuK for ; Mon, 19 Apr 2010 19:42:34 -0700 (PDT) From: Dave Chinner Subject: [PATCH 3/4] writeback: pay attention to wbc->nr_to_write in write_cache_pages Date: Tue, 20 Apr 2010 12:41:53 +1000 Message-Id: <1271731314-5893-4-git-send-email-david@fromorbit.com> In-Reply-To: <1271731314-5893-1-git-send-email-david@fromorbit.com> References: <1271731314-5893-1-git-send-email-david@fromorbit.com> MIME-Version: 1.0 List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, xfs@oss.sgi.com RnJvbTogRGF2ZSBDaGlubmVyIDxkY2hpbm5lckByZWRoYXQuY29tPgoKSWYgYSBmaWxlc3lzdGVt IHdyaXRlcyBtb3JlIHRoYW4gb25lIHBhZ2UgaW4gLT53cml0ZXBhZ2UsIHdyaXRlX2NhY2hlX3Bh Z2VzCmZhaWxzIHRvIG5vdGljZSB0aGlzIGFuZCBjb250aW51ZXMgdG8gYXR0ZW1wdCB3cml0ZWJh Y2sgd2hlbiB3YmMtPm5yX3RvX3dyaXRlCmhhcyBnb25lIG5lZ2F0aXZlIC0gdGhpcyB0cmFjZSB3 YXMgY2FwdHVyZWQgZnJvbSBYRlM6CgoKICAgIHdiY193cml0ZWJhY2tfc3RhcnQ6IHRvd3J0PTEw MjQKICAgIHdiY193cml0ZXBhZ2U6IHRvd3J0PTEwMjQKICAgIHdiY193cml0ZXBhZ2U6IHRvd3J0 PTAKICAgIHdiY193cml0ZXBhZ2U6IHRvd3J0PS0xCiAgICB3YmNfd3JpdGVwYWdlOiB0b3dydD0t NQogICAgd2JjX3dyaXRlcGFnZTogdG93cnQ9LTIxCiAgICB3YmNfd3JpdGVwYWdlOiB0b3dydD0t ODUKClRoaXMgaGFzIGFkdmVyc2UgZWZmZWN0cyBvbiBmaWxlc3lzdGVtIHdyaXRlYmFjayBiZWhh 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CQl9CiAJCX0KIAkJcGFnZXZlY19yZWxlYXNlKCZwdmVjKTsKIAkJY29uZF9yZXNjaGVkKCk7Ci0t IAoxLjYuNQoKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18K eGZzIG1haWxpbmcgbGlzdAp4ZnNAb3NzLnNnaS5jb20KaHR0cDovL29zcy5zZ2kuY29tL21haWxt YW4vbGlzdGluZm8veGZzCg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753405Ab0DTCnc (ORCPT ); Mon, 19 Apr 2010 22:43:32 -0400 Received: from bld-mail17.adl2.internode.on.net ([150.101.137.102]:43544 "EHLO mail.internode.on.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753079Ab0DTCmi (ORCPT ); Mon, 19 Apr 2010 22:42:38 -0400 From: Dave Chinner To: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, xfs@oss.sgi.com Subject: [PATCH 3/4] writeback: pay attention to wbc->nr_to_write in write_cache_pages Date: Tue, 20 Apr 2010 12:41:53 +1000 Message-Id: <1271731314-5893-4-git-send-email-david@fromorbit.com> X-Mailer: git-send-email 1.6.5 In-Reply-To: <1271731314-5893-1-git-send-email-david@fromorbit.com> References: <1271731314-5893-1-git-send-email-david@fromorbit.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dave Chinner If a filesystem writes more than one page in ->writepage, write_cache_pages fails to notice this and continues to attempt writeback when wbc->nr_to_write has gone negative - this trace was captured from XFS: wbc_writeback_start: towrt=1024 wbc_writepage: towrt=1024 wbc_writepage: towrt=0 wbc_writepage: towrt=-1 wbc_writepage: towrt=-5 wbc_writepage: towrt=-21 wbc_writepage: towrt=-85 This has adverse effects on filesystem writeback behaviour. write_cache_pages() needs to terminate after a certain number of pages are written, not after a certain number of calls to ->writepage are made. Make it observe the current value of wbc->nr_to_write and treat a value of <= 0 as though it is a either a termination condition or a trigger to reset to MAX_WRITEḆACK_PAGES for data integrity syncs. Signed-off-by: Dave Chinner --- fs/fs-writeback.c | 9 --------- include/linux/writeback.h | 9 +++++++++ include/trace/events/writeback.h | 1 + mm/page-writeback.c | 20 +++++++++++++++++++- 4 files changed, 29 insertions(+), 10 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 5214b61..d8271d5 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -675,15 +675,6 @@ void writeback_inodes_wbc(struct writeback_control *wbc) writeback_inodes_wb(&bdi->wb, wbc); } -/* - * The maximum number of pages to writeout in a single bdi flush/kupdate - * operation. We do this so we don't hold I_SYNC against an inode for - * enormous amounts of time, which would block a userspace task which has - * been forced to throttle against that inode. Also, the code reevaluates - * the dirty each time it has written this many pages. - */ -#define MAX_WRITEBACK_PAGES 1024 - static inline bool over_bground_thresh(void) { unsigned long background_thresh, dirty_thresh; diff --git a/include/linux/writeback.h b/include/linux/writeback.h index b2d615f..8533a0f 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -14,6 +14,15 @@ extern struct list_head inode_in_use; extern struct list_head inode_unused; /* + * The maximum number of pages to writeout in a single bdi flush/kupdate + * operation. We do this so we don't hold I_SYNC against an inode for + * enormous amounts of time, which would block a userspace task which has + * been forced to throttle against that inode. Also, the code reevaluates + * the dirty each time it has written this many pages. + */ +#define MAX_WRITEBACK_PAGES 1024 + +/* * fs/fs-writeback.c */ enum writeback_sync_modes { diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h index 02f34a5..3bcbd83 100644 --- a/include/trace/events/writeback.h +++ b/include/trace/events/writeback.h @@ -241,6 +241,7 @@ DEFINE_WBC_EVENT(wbc_writeback_wait); DEFINE_WBC_EVENT(wbc_balance_dirty_start); DEFINE_WBC_EVENT(wbc_balance_dirty_written); DEFINE_WBC_EVENT(wbc_balance_dirty_wait); +DEFINE_WBC_EVENT(wbc_writepage); #endif /* _TRACE_WRITEBACK_H */ diff --git a/mm/page-writeback.c b/mm/page-writeback.c index d45f59e..e22af84 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -917,6 +917,7 @@ continue_unlock: if (!clear_page_dirty_for_io(page)) goto continue_unlock; + trace_wbc_writepage(wbc); ret = (*writepage)(page, wbc, data); if (unlikely(ret)) { if (ret == AOP_WRITEPAGE_ACTIVATE) { @@ -935,7 +936,7 @@ continue_unlock: done = 1; break; } - } + } if (nr_to_write > 0) { nr_to_write--; @@ -955,6 +956,23 @@ continue_unlock: break; } } + + /* + * Some filesystems will write multiple pages in + * ->writepage, so wbc->nr_to_write can change much, + * much faster than nr_to_write. Check this as an exit + * condition, or if we are doing a data integrity sync, + * reset the wbc to MAX_WRITEBACK_PAGES so that such + * filesystems can do optimal writeout here. + */ + if (wbc->nr_to_write <= 0) { + if (wbc->sync_mode == WB_SYNC_NONE) { + done = 1; + nr_to_write = 0; + break; + } + wbc->nr_to_write = MAX_WRITEBACK_PAGES; + } } pagevec_release(&pvec); cond_resched(); -- 1.6.5