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From: Wu Fengguang <fengguang.wu@intel.com>
To: Michael Rubin <mrubin@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"jack@suse.cz" <jack@suse.cz>,
	"riel@redhat.com" <riel@redhat.com>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"david@fromorbit.com" <david@fromorbit.com>,
	"npiggin@kernel.dk" <npiggin@kernel.dk>,
	"hch@lst.de" <hch@lst.de>, "axboe@kernel.dk" <axboe@kernel.dk>
Subject: Re: [PATCH 4/4] writeback: Reporting dirty thresholds in /proc/vmstat
Date: Sat, 21 Aug 2010 13:48:08 +0800	[thread overview]
Message-ID: <20100821054808.GA29869@localhost> (raw)
In-Reply-To: <1282296689-25618-5-git-send-email-mrubin@google.com>

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

I realized that the dirty thresholds has already been exported here:

$ grep Thresh  /debug/bdi/8:0/stats
BdiDirtyThresh:     381000 kB
DirtyThresh:       1719076 kB
BackgroundThresh:   859536 kB

So why not use that interface directly?

Thanks,
Fengguang

WARNING: multiple messages have this Message-ID (diff)
From: Wu Fengguang <fengguang.wu@intel.com>
To: Michael Rubin <mrubin@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"jack@suse.cz" <jack@suse.cz>,
	"riel@redhat.com" <riel@redhat.com>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"david@fromorbit.com" <david@fromorbit.com>,
	"npiggin@kernel.dk" <npiggin@kernel.dk>,
	"hch@lst.de" <hch@lst.de>, "axboe@kernel.dk" <axboe@kernel.dk>
Subject: Re: [PATCH 4/4] writeback: Reporting dirty thresholds in /proc/vmstat
Date: Sat, 21 Aug 2010 13:48:08 +0800	[thread overview]
Message-ID: <20100821054808.GA29869@localhost> (raw)
In-Reply-To: <1282296689-25618-5-git-send-email-mrubin@google.com>

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

I realized that the dirty thresholds has already been exported here:

$ grep Thresh  /debug/bdi/8:0/stats
BdiDirtyThresh:     381000 kB
DirtyThresh:       1719076 kB
BackgroundThresh:   859536 kB

So why not use that interface directly?

Thanks,
Fengguang

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  parent reply	other threads:[~2010-08-21  5:48 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-08-20  9:31 [PATCH 0/4] writeback: kernel visibility Michael Rubin
2010-08-20  9:31 ` Michael Rubin
2010-08-20  9:31 ` [PATCH 1/4] mm: exporting account_page_dirty Michael Rubin
2010-08-20  9:31   ` Michael Rubin
2010-08-20  9:39   ` Wu Fengguang
2010-08-20  9:39     ` Wu Fengguang
2010-08-20 15:37     ` Sage Weil
2010-08-20 15:37       ` Sage Weil
2010-08-20  9:31 ` [PATCH 2/4] mm: account_page_writeback added Michael Rubin
2010-08-20  9:31   ` Michael Rubin
2010-08-20  9:45   ` Wu Fengguang
2010-08-20  9:45     ` Wu Fengguang
2010-08-20 10:08     ` KOSAKI Motohiro
2010-08-20 10:08       ` KOSAKI Motohiro
2010-08-20  9:31 ` [PATCH 3/4] writeback: nr_dirtied and nr_entered_writeback in /proc/vmstat Michael Rubin
2010-08-20  9:31   ` Michael Rubin
2010-08-20 10:05   ` KOSAKI Motohiro
2010-08-20 10:05     ` KOSAKI Motohiro
2010-08-20 10:08   ` Wu Fengguang
2010-08-20 10:08     ` Wu Fengguang
2010-08-20 23:51     ` Michael Rubin
2010-08-20 23:51       ` Michael Rubin
2010-08-21  0:48       ` Wu Fengguang
2010-08-21  0:48         ` Wu Fengguang
2010-08-21  0:48         ` Wu Fengguang
2010-08-23 17:45         ` Michael Rubin
2010-08-23 17:45           ` Michael Rubin
2010-08-24  2:30           ` Wu Fengguang
2010-08-24  2:30             ` Wu Fengguang
2010-08-24  3:02             ` Michael Rubin
2010-08-24  3:02               ` Michael Rubin
2010-08-24  3:25               ` Wu Fengguang
2010-08-24  3:25                 ` Wu Fengguang
2010-08-20  9:31 ` [PATCH 4/4] writeback: Reporting dirty thresholds " Michael Rubin
2010-08-20  9:31   ` Michael Rubin
2010-08-20 10:06   ` KOSAKI Motohiro
2010-08-20 10:06     ` KOSAKI Motohiro
2010-08-22 10:27     ` KOSAKI Motohiro
2010-08-22 10:27       ` KOSAKI Motohiro
2010-08-22 10:27       ` KOSAKI Motohiro
2010-08-20 10:12   ` Wu Fengguang
2010-08-20 10:12     ` Wu Fengguang
2010-08-21  5:48   ` Wu Fengguang [this message]
2010-08-21  5:48     ` Wu Fengguang
2010-08-23 17:52     ` Michael Rubin
2010-08-23 17:52       ` Michael Rubin
2010-08-24  1:20       ` KOSAKI Motohiro
2010-08-24  1:20         ` KOSAKI Motohiro
2010-08-24  1:41         ` Michael Rubin
2010-08-24  1:41           ` Michael Rubin
2010-08-24  1:41           ` Michael Rubin
2010-08-24  2:11           ` Wu Fengguang
2010-08-24  2:42             ` Michael Rubin
2010-08-24  2:42               ` Michael Rubin
2010-08-24  2:01   ` Wu Fengguang
2010-08-24  2:01     ` Wu Fengguang
2010-08-24  2:04     ` Michael Rubin
2010-08-24  2:04       ` Michael Rubin
2010-08-24  2:04       ` Michael Rubin
  -- strict thread matches above, loose matches on Subject: below --
2010-08-28  2:40 [PATCH 0/4] writeback: kernel visibility Michael Rubin
2010-08-28  2:40 ` [PATCH 4/4] writeback: Reporting dirty thresholds in /proc/vmstat Michael Rubin
2010-08-28  2:40   ` Michael Rubin
2010-08-30  0:28   ` KOSAKI Motohiro
2010-08-30  0:28     ` KOSAKI Motohiro
2010-08-30 16:25     ` Michael Rubin
2010-08-30 16:25       ` Michael Rubin
2010-08-31  1:07       ` KOSAKI Motohiro
2010-08-31  1:07         ` KOSAKI Motohiro
2010-08-31  1:32         ` Wu Fengguang
2010-08-31  1:32           ` Wu Fengguang

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