From: James Bottomley <James.Bottomley@SteelEye.com>
To: Andrew Morton <akpm@osdl.org>
Cc: luben_tuikov@adaptec.com, jim.houston@ccur.com,
Linux Kernel <linux-kernel@vger.kernel.org>,
SCSI Mailing List <linux-scsi@vger.kernel.org>,
Dave Jones <davej@redhat.com>, Jeff Garzik <jgarzik@pobox.com>
Subject: Re: [PATCH 2.6.12.5 1/2] lib: allow idr to be used in irq context
Date: Mon, 22 Aug 2005 16:53:35 -0500 [thread overview]
Message-ID: <1124747615.5211.34.camel@mulgrave> (raw)
In-Reply-To: <1124720938.5211.13.camel@mulgrave>
On Mon, 2005-08-22 at 09:28 -0500, James Bottomley wrote:
> > I think providing locking inside idr.c was always a mistake - generally we
> > rely on caller-provided locking for such things.
>
> Well, the reason is because they wanted lockless pre-alloc. If you do
> it locked, you can't use GFP_KERNEL for the memory allocation flag which
> rather defeats its purpose.
It looks to be feasible to implement this locklessly the same way as the
radix-tree does (with a per_cpu list), except that you still need a
start/end API for the pre allocation to do the initial disable of pre-
emption.
Then the remove should simply then free the entry (again like radix-
tree) and let the slab take care of necessary locking.
Of course, if we're going to go to all this trouble, the next question
that arises naturally is why not just reuse the radix-tree code to
implement idr anyway ... ?
James
next prev parent reply other threads:[~2005-08-22 21:54 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-08-16 22:03 [PATCH 2.6.12.5 1/2] lib: allow idr to be used in irq context Luben Tuikov
2005-08-17 16:01 ` Jim Houston
2005-08-21 8:25 ` Andrew Morton
2005-08-21 15:49 ` Luben Tuikov
2005-08-21 16:06 ` James Bottomley
2005-08-21 17:27 ` Luben Tuikov
2005-08-21 22:03 ` James Bottomley
2005-08-22 0:33 ` Luben Tuikov
2005-08-22 3:15 ` James Bottomley
2005-08-22 3:52 ` Andrew Morton
2005-08-22 14:28 ` James Bottomley
2005-08-22 16:51 ` Luben Tuikov
2005-08-22 21:53 ` James Bottomley [this message]
2005-08-22 22:09 ` Andrew Morton
2005-08-23 17:15 ` James Bottomley
2005-08-22 16:33 ` Luben Tuikov
2005-08-22 14:06 ` Luben Tuikov
-- strict thread matches above, loose matches on Subject: below --
2005-08-21 20:40 Luben Tuikov
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