From: Christoph Hellwig <hch@infradead.org>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: axboe@kernel.dk, linux-kernel@vger.kernel.org,
Christoph Hellwig <hch@infradead.org>,
dm-devel <dm-devel@redhat.com>,
Alasdair G Kergon <agk@redhat.com>
Subject: Re: Queue upcall locking (was: [RFC][PATCH] fix dm_any_congested() to properly sync up with suspend code path)
Date: Tue, 11 Nov 2008 13:18:54 -0500 [thread overview]
Message-ID: <20081111181854.GA25049@infradead.org> (raw)
In-Reply-To: <Pine.LNX.4.64.0811100914500.14825@hs20-bc2-1.build.redhat.com>
On Mon, Nov 10, 2008 at 09:19:21AM -0500, Mikulas Patocka wrote:
> For device mapper, congested_fn asks every device in the tree and make OR
> of their bits --- so if the user has 50 devices, it asks them all.
>
> For md-linear, md-raid0, md-raid1, md-raid10 and md-multipath it does the
> same --- asking every device.
>
> If you have a better idea how to implement congested_fn, say it.
Well, even asking 50 devices shouldn't take that long normally. Do you
take some sleeping lock that might block forever? In that case I would
just return congested for that device as it would delay pdflush
otherwise.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@infradead.org>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Chandra Seetharaman <sekharan@us.ibm.com>,
Alasdair G Kergon <agk@redhat.com>,
dm-devel <dm-devel@redhat.com>,
linux-kernel@vger.kernel.org, axboe@kernel.dk
Subject: Re: Queue upcall locking (was: [dm-devel] [RFC][PATCH] fix dm_any_congested() to properly sync up with suspend code path)
Date: Tue, 11 Nov 2008 13:18:54 -0500 [thread overview]
Message-ID: <20081111181854.GA25049@infradead.org> (raw)
In-Reply-To: <Pine.LNX.4.64.0811100914500.14825@hs20-bc2-1.build.redhat.com>
On Mon, Nov 10, 2008 at 09:19:21AM -0500, Mikulas Patocka wrote:
> For device mapper, congested_fn asks every device in the tree and make OR
> of their bits --- so if the user has 50 devices, it asks them all.
>
> For md-linear, md-raid0, md-raid1, md-raid10 and md-multipath it does the
> same --- asking every device.
>
> If you have a better idea how to implement congested_fn, say it.
Well, even asking 50 devices shouldn't take that long normally. Do you
take some sleeping lock that might block forever? In that case I would
just return congested for that device as it would delay pdflush
otherwise.
next prev parent reply other threads:[~2008-11-11 18:18 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-11-06 4:00 [RFC][PATCH] fix dm_any_congested() to properly sync up with suspend code path Chandra Seetharaman
2008-11-10 13:11 ` Queue upcall locking (was: [RFC][PATCH] fix dm_any_congested() to properly sync up with suspend code path) Mikulas Patocka
2008-11-10 13:11 ` Queue upcall locking (was: [dm-devel] " Mikulas Patocka
2008-11-10 13:54 ` Queue upcall locking (was: " Christoph Hellwig
2008-11-10 13:54 ` Queue upcall locking (was: [dm-devel] " Christoph Hellwig
2008-11-10 14:19 ` Queue upcall locking (was: " Mikulas Patocka
2008-11-10 14:19 ` Queue upcall locking (was: [dm-devel] " Mikulas Patocka
2008-11-10 14:26 ` Peter Zijlstra
2008-11-10 14:32 ` Queue upcall locking (was: " Mikulas Patocka
2008-11-10 14:32 ` Queue upcall locking (was: [dm-devel] " Mikulas Patocka
2008-11-10 14:46 ` Peter Zijlstra
2008-11-10 14:55 ` Queue upcall locking (was: " Mikulas Patocka
2008-11-10 14:55 ` Queue upcall locking (was: [dm-devel] " Mikulas Patocka
2008-11-10 14:35 ` Queue upcall locking (was: " Alasdair G Kergon
2008-11-10 14:35 ` Queue upcall locking (was: [dm-devel] " Alasdair G Kergon
2008-11-11 18:18 ` Christoph Hellwig [this message]
2008-11-11 18:18 ` Christoph Hellwig
2008-11-11 22:08 ` Queue upcall locking (was: " Mikulas Patocka
2008-11-11 22:08 ` Queue upcall locking (was: [dm-devel] " Mikulas Patocka
2008-11-10 14:27 ` Queue upcall locking (was: " Alasdair G Kergon
2008-11-10 14:27 ` Queue upcall locking (was: [dm-devel] " Alasdair G Kergon
2008-11-10 14:40 ` Queue upcall locking (was: " Mikulas Patocka
2008-11-10 14:40 ` Queue upcall locking (was: [dm-devel] " Mikulas Patocka
2008-11-11 18:22 ` Christoph Hellwig
2008-11-11 18:21 ` Christoph Hellwig
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