Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752160Ab0HTKM7 (ORCPT ); Fri, 20 Aug 2010 06:12:59 -0400 Received: from mga09.intel.com ([134.134.136.24]:37283 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751499Ab0HTKM5 (ORCPT ); Fri, 20 Aug 2010 06:12:57 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.56,238,1280732400"; d="scan'208";a="547116360" Date: Fri, 20 Aug 2010 18:12:51 +0800 From: Wu Fengguang To: Michael Rubin Cc: "linux-kernel@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , "jack@suse.cz" , "riel@redhat.com" , "akpm@linux-foundation.org" , "david@fromorbit.com" , "npiggin@kernel.dk" , "hch@lst.de" , "axboe@kernel.dk" Subject: Re: [PATCH 4/4] writeback: Reporting dirty thresholds in /proc/vmstat Message-ID: <20100820101251.GD8440@localhost> References: <1282296689-25618-1-git-send-email-mrubin@google.com> <1282296689-25618-5-git-send-email-mrubin@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1282296689-25618-5-git-send-email-mrubin@google.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1530 Lines: 39 On Fri, Aug 20, 2010 at 05:31:29PM +0800, Michael Rubin wrote: > The kernel already exposes the user desired thresholds in /proc/sys/vm > with dirty_background_ratio and background_ratio. But the kernel may > alter the number requested without giving the user any indication that > is the case. > > Knowing the actual ratios the kernel is honoring can help app developers > understand how their buffered IO will be sent to the disk. > > $ grep threshold /proc/vmstat > nr_dirty_threshold 409111 > nr_dirty_background_threshold 818223 > > Signed-off-by: Michael Rubin > --- > include/linux/mmzone.h | 3 +++ > mm/vmstat.c | 5 +++++ > 2 files changed, 8 insertions(+), 0 deletions(-) > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index fe4e6dd..c2243d0 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -106,6 +106,9 @@ enum zone_stat_item { > NR_SHMEM, /* shmem pages (included tmpfs/GEM pages) */ > NR_FILE_PAGES_DIRTIED, /* number of times pages get dirtied */ > NR_PAGES_ENTERED_WRITEBACK, /* number of times pages enter writeback */ > + NR_DIRTY_THRESHOLD, /* writeback threshold */ > + NR_DIRTY_BG_THRESHOLD, /* bg writeback threshold */ This may cost cacheline. Thanks, Fengguang -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/