Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752063Ab0HTDQy (ORCPT ); Thu, 19 Aug 2010 23:16:54 -0400 Received: from mga01.intel.com ([192.55.52.88]:45783 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751042Ab0HTDQw (ORCPT ); Thu, 19 Aug 2010 23:16:52 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.56,237,1280732400"; d="scan'208";a="830009592" Date: Fri, 20 Aug 2010 11:16:48 +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@suse.de, hch@lst.de, axboe@kernel.dk Subject: Re: [PATCH 3/3] writeback: Reporting dirty thresholds in /proc/vmstat Message-ID: <20100820031647.GC5502@localhost> References: <1282251447-16937-1-git-send-email-mrubin@google.com> <1282251447-16937-4-git-send-email-mrubin@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1282251447-16937-4-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: 3531 Lines: 106 On Thu, Aug 19, 2010 at 01:57:27PM -0700, Michael Rubin wrote: > The kernel already exposes the desired thresholds in /proc/sys/vm with > dirty_background_ratio and background_ratio. Instead the kernel may > alter the number requested without giving the user any indication that > is the case. You mean the 5% lower bound in global_dirty_limits()? Let's rip it :) > 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_pages_dirty_threshold 409111 > nr_pages_dirty_background_threshold 818223 It's redundant to have _pages in the names. /proc/vmstat has the tradition to use nr_dirty instead of nr_pages_dirty. They do look like useful counters to export, especially when we do dynamic dirty limits in future. > Signed-off-by: Michael Rubin > --- > include/linux/mmzone.h | 2 ++ > mm/vmstat.c | 8 ++++++++ > 2 files changed, 10 insertions(+), 0 deletions(-) > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index f160481..7c4a3bf 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -114,6 +114,8 @@ enum zone_stat_item { > #endif > NR_PAGES_ENTERED_WRITEBACK, /* number of times pages enter writeback */ > NR_FILE_PAGES_DIRTIED, /* number of times pages get dirtied */ > + NR_PAGES_DIRTY_THRESHOLD, /* writeback threshold */ > + NR_PAGES_DIRTY_BG_THRESHOLD,/* bg writeback threshold */ s/_PAGES// > NR_VM_ZONE_STAT_ITEMS }; > > /* > diff --git a/mm/vmstat.c b/mm/vmstat.c > index e177a40..8b5bc78 100644 > --- a/mm/vmstat.c > +++ b/mm/vmstat.c > @@ -17,6 +17,7 @@ > #include > #include > #include > +#include > > #ifdef CONFIG_VM_EVENT_COUNTERS > DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}}; > @@ -742,6 +743,8 @@ static const char * const vmstat_text[] = { > #endif > "nr_pages_entered_writeback", > "nr_file_pages_dirtied", > + "nr_pages_dirty_threshold", > + "nr_pages_dirty_background_threshold", s/_pages// > #ifdef CONFIG_VM_EVENT_COUNTERS > "pgpgin", > @@ -901,6 +904,7 @@ static void *vmstat_start(struct seq_file *m, loff_t *pos) > #ifdef CONFIG_VM_EVENT_COUNTERS > unsigned long *e; > #endif > + unsigned long dirty_thresh, dirty_bg_thresh; > int i; > > if (*pos >= ARRAY_SIZE(vmstat_text)) > @@ -918,6 +922,10 @@ static void *vmstat_start(struct seq_file *m, loff_t *pos) > return ERR_PTR(-ENOMEM); > for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) > v[i] = global_page_state(i); > + > + get_dirty_limits(&dirty_thresh, &dirty_bg_thresh, NULL, NULL); 2.6.36-rc1 will need this: global_dirty_limits(v + NR_DIRTY_THRESHOLD, v + NR_DIRTY_BG_THRESHOLD); Thanks, Fengguang > + v[NR_PAGES_DIRTY_THRESHOLD] = dirty_thresh; > + v[NR_PAGES_DIRTY_BG_THRESHOLD] = dirty_bg_thresh; > #ifdef CONFIG_VM_EVENT_COUNTERS > e = v + NR_VM_ZONE_STAT_ITEMS; > all_vm_events(e); > -- > 1.7.1 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org -- 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/