From: Bill Davidsen <davidsen@tmr.com>
To: linux-kernel@vger.kernel.org
Subject: Re: f_ops flag to speed up compatible ioctls in linux kernel
Date: Wed, 01 Sep 2004 14:06:16 -0400 [thread overview]
Message-ID: <ch52km$grt$1@gatekeeper.tmr.com> (raw)
In-Reply-To: <20040901073218.GQ16297@parcelfarce.linux.theplanet.co.uk>
viro@parcelfarce.linux.theplanet.co.uk wrote:
> On Wed, Sep 01, 2004 at 10:22:45AM +0300, Michael S. Tsirkin wrote:
>
>>Hello!
>>Currently, on the x86_64 architecture, its quite tricky to make
>>a char device ioctl work for an x86 executables.
>>In particular,
>> 1. there is a requirement that ioctl number is unique -
>> which is hard to guarantee especially for out of kernel modules
>
>
> Too bad.
>
>
>> 2. there's a performance huge overhead for each compat call - there's
>> a hash lookup in a global hash inside a lock_kernel -
>> and I think compat performance *is* important.
>>
>>Further, adding a command to the ioctl suddenly requires changing
>>two places - registration code and ioctl itself.
>
>
> So don't add them. Adding a new ioctl is *NOT* a step to be taken lightly -
> we used to be far too accepting in that area and as somebody who'd waded
> through the resulting dungpiles over the last months I can tell you that
> result is utterly revolting.
>
> Excuse me, but I have zero sympathy to people who complain about obstacles
> to dumping more into the same piles - it should be hard.
I don't think he was complaining so much as providing a rationale for
the patch he offered which is intended to make things better. Seemed to
me like a good context for the patch.
--
-bill davidsen (davidsen@tmr.com)
"The secret to procrastination is to put things off until the
last possible moment - but no longer" -me
next prev parent reply other threads:[~2004-09-01 18:08 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-01 7:22 f_ops flag to speed up compatible ioctls in linux kernel Michael S. Tsirkin
2004-09-01 7:32 ` viro
2004-09-01 7:44 ` Michael S. Tsirkin
2004-09-01 7:47 ` Lee Revell
2004-09-01 8:19 ` Michael S. Tsirkin
2004-09-01 15:55 ` Roland Dreier
2004-09-01 18:02 ` Chris Wright
2004-09-01 18:12 ` Roland Dreier
2004-09-01 18:31 ` viro
2004-09-01 20:54 ` Roland Dreier
[not found] ` <20040901170800.K1924@build.pdx.osdl.net>
[not found] ` <20040901190122.L1924@build.pdx.osdl.net>
2004-09-02 3:46 ` Roland Dreier
2004-09-01 18:06 ` Bill Davidsen [this message]
2004-09-01 8:30 ` Arjan van de Ven
2004-09-01 15:40 ` [PATCH] fs/compat.c: rwsem instead of BKL around ioctl32_hash_table Roland Dreier
2004-09-01 23:27 ` Andrew Morton
2004-09-02 21:14 ` Andi Kleen
2004-09-02 22:26 ` Roland Dreier
2004-09-03 14:37 ` [discuss] " Andi Kleen
2004-09-03 14:55 ` Roland Dreier
2004-09-03 15:02 ` Andi Kleen
2004-09-03 8:00 ` [discuss] f_ops flag to speed up compatible ioctls in linux kernel Andi Kleen
2004-09-07 10:40 ` Michael S. Tsirkin
2004-09-07 12:14 ` Andi Kleen
2004-09-07 13:45 ` Michael S. Tsirkin
2004-09-07 14:15 ` Andi Kleen
2004-09-07 14:25 ` Michael S. Tsirkin
2004-09-07 14:29 ` Andi Kleen
2004-09-07 14:37 ` Michael S. Tsirkin
2004-09-07 14:44 ` Andi Kleen
2004-09-07 14:45 ` Michael S. Tsirkin
2004-09-07 15:10 ` Andi Kleen
2004-09-07 18:16 ` Michael S. Tsirkin
2004-09-08 6:55 ` Andi Kleen
2004-09-08 14:28 ` [patch] " Michael S. Tsirkin
2004-09-08 14:38 ` Andi Kleen
2004-09-08 14:54 ` Michael S. Tsirkin
2004-09-08 14:58 ` Andi Kleen
2004-09-12 20:05 ` Michael S. Tsirkin
2004-09-15 13:19 ` [patch] Re: [discuss] " Michael S. Tsirkin
2004-09-07 21:36 ` Is FIOQSIZE compatible? ( was Re: f_ops flag to speed up compatible ioctls in linux kernel) Michael S. Tsirkin
2004-09-08 6:54 ` Andi Kleen
2004-09-07 15:03 ` [discuss] f_ops flag to speed up compatible ioctls in linux kernel Herbert Poetzl
2004-09-07 18:07 ` Michael S. Tsirkin
2004-09-09 13:54 ` Herbert Poetzl
2004-12-12 21:51 ` how to detect a 32 bit process on 64 bit kernel Michael S. Tsirkin
2004-12-12 22:01 ` Jan Engelhardt
2004-12-12 22:23 ` Christoph Hellwig
2004-12-13 19:50 ` Michael S. Tsirkin
2004-12-13 21:01 ` Jan Engelhardt
2004-12-13 21:32 ` Brian Gerst
2004-12-13 21:37 ` Michael S. Tsirkin
2004-12-12 22:37 ` Willy Tarreau
2004-12-12 23:30 ` Bongani Hlope
2004-12-14 7:28 ` Andi Kleen
2004-09-20 14:49 ` [patch] speed up ioctls in linux kernel Michael S. Tsirkin
2004-09-01 9:50 f_ops flag to speed up compatible " filia
2004-09-01 9:52 ` Arjan van de Ven
2004-09-01 10:16 ` filia
[not found] ` <4135B9FC.7050602@hist.no>
2004-09-01 13:29 ` Ihar 'Philips' Filipau
2004-09-01 15:28 ` Ihar 'Philips' Filipau
2004-09-02 7:29 ` Helge Hafting
2004-09-01 13:43 ` Olivier Galibert
2004-09-01 15:36 Albert Cahalan
2004-09-01 15:59 ` Roland Dreier
2004-09-01 21:53 ` Michael S. Tsirkin
2004-09-01 22:58 ` Roland Dreier
2004-09-01 23:18 ` Michael S. Tsirkin
2004-09-01 15:40 Albert Cahalan
2004-09-01 21:23 ` Michael S. Tsirkin
2004-09-01 21:38 ` Lee Revell
2004-09-01 21:43 ` Chris Wright
2004-09-01 21:44 ` Roland Dreier
2004-12-27 22:22 Michael S. Tsirkin
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