From: Mark Lord <lkml@rtr.ca>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Vadim Lobanov <vlobanov@speakeasy.net>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
lkml <linux-kernel@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC][PATCH] irq: remove IRQF_DISABLED
Date: Thu, 05 Mar 2009 10:40:44 -0500 [thread overview]
Message-ID: <49AFF27C.1020001@rtr.ca> (raw)
In-Reply-To: <alpine.LFD.2.00.0903021048570.3111@localhost.localdomain>
Linus Torvalds wrote:
>
> Although it porbably does mean that the problem tends to be more in the
> really bad mode0 case (600ns -> 150us/sector -> milliseconds for
> multi-sector transfers).
..
Heh.. it's worse that that: even with commonplace mode4 (120ns) transfers,
each PCI bus transaction from start to finish often takes about 1us,
so for a 16-sector multi-sector read, that means 4ms+ with interrupts off.
> I forget what our multi-sector limit is, I think it tends to be 16. So
> you'll never get _really_ long irq-off times, but "several ms" is still
> pretty damn bad.
..
It's a device limit, usually 8 or 16 sectors for nearly all drives now.
Cheers
next prev parent reply other threads:[~2009-03-05 15:40 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-02 12:21 [RFC][PATCH] irq: remove IRQF_DISABLED Peter Zijlstra
2009-03-02 14:43 ` Ingo Molnar
2009-03-02 15:47 ` Matthew Wilcox
2009-03-02 15:59 ` Peter Zijlstra
2009-03-02 16:32 ` Matthew Wilcox
2009-03-02 21:01 ` Russell King
2009-03-02 21:17 ` Ingo Molnar
2009-03-02 21:17 ` Ingo Molnar
2009-03-02 17:11 ` Linus Torvalds
2009-03-02 17:55 ` Bartlomiej Zolnierkiewicz
2009-03-02 18:02 ` Peter Zijlstra
2009-03-02 18:07 ` Peter Zijlstra
2009-03-02 18:27 ` Bartlomiej Zolnierkiewicz
2009-03-02 18:29 ` Linus Torvalds
2009-03-02 18:48 ` Bartlomiej Zolnierkiewicz
2009-03-02 19:06 ` Linus Torvalds
2009-03-02 19:18 ` Bartlomiej Zolnierkiewicz
2009-03-02 17:56 ` Peter Zijlstra
2009-03-02 18:45 ` Vadim Lobanov
2009-03-02 18:54 ` Linus Torvalds
2009-03-05 15:40 ` Mark Lord [this message]
2009-03-02 21:17 ` Alan Cox
2009-03-06 8:58 ` Benjamin Herrenschmidt
2009-03-06 9:12 ` Peter Zijlstra
2009-03-06 9:59 ` Benjamin Herrenschmidt
2009-03-06 10:05 ` Benjamin Herrenschmidt
2009-03-06 10:24 ` Peter Zijlstra
2009-03-06 17:02 ` Peter Zijlstra
2009-03-06 21:40 ` Benjamin Herrenschmidt
2009-03-02 17:55 ` Andrew Morton
2009-03-02 18:10 ` Peter Zijlstra
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