From: Mark Lord <lkml@rtr.ca>
To: Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@osdl.org>, Ingo Molnar <mingo@elte.hu>,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: CONFIG_IRQBALANCE for 64-bit x86 ?
Date: Mon, 19 Nov 2007 23:12:21 -0500 [thread overview]
Message-ID: <47425EA5.7000607@rtr.ca> (raw)
On 32-bit x86, we have CONFIG_IRQBALANCE available,
but not on 64-bit x86. Why not?
I ask, because this feature seems almost essential to obtaining
reasonable latencies during heavy I/O with fast devices.
My 32-bit Core2Duo MythTV box drops audio frames without it,
but works perfectly *with* IRQBALANCE.
My QuadCore box works very well in 32-bit mode with IRQBALANCE,
but responsiveness sucks bigtime when run in 64-bit mode (no IRQBALANCE)
during periods of multiple heavy I/O streams (USB flash drives).
That's with both the 32 and 64 bit versions of Kubuntu Gutsy,
so the software uses pretty much identical versions either way.
As near as I can tell, when IRQBALANCE is not configured,
all I/O device interrupts go to CPU#0.
I don't think our CPU scheduler takes that into account when assigning
tasks to CPUs, so anything sent to CPU0 runs with very high latencies.
Or something like that.
Why no IRQ_BALANCE in 64-bit mode ?
next reply other threads:[~2007-11-20 4:12 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-20 4:12 Mark Lord [this message]
2007-11-20 4:15 ` CONFIG_IRQBALANCE for 64-bit x86 ? Ismail Dönmez
2007-11-20 4:17 ` Nick Piggin
2007-11-20 4:29 ` Willy Tarreau
2007-11-20 4:37 ` Adrian Bunk
2007-11-20 5:24 ` Nick Piggin
2007-11-20 5:28 ` H. Peter Anvin
2007-11-20 5:37 ` Arjan van de Ven
2007-11-20 7:37 ` Nick Piggin
2007-11-20 14:47 ` Arjan van de Ven
2007-11-20 15:43 ` Nick Piggin
2007-11-20 19:07 ` Arjan van de Ven
2007-11-20 20:02 ` Mark Lord
2007-11-20 21:58 ` Arjan van de Ven
2007-11-20 23:17 ` Mark Lord
2007-11-22 7:54 ` Nick Piggin
2007-11-23 13:09 ` Ingo Molnar
2007-11-25 10:03 ` Nick Piggin
2007-11-20 15:47 ` Mark Lord
2007-11-20 15:52 ` Mark Lord
2007-11-20 16:02 ` Arjan van de Ven
2007-11-20 16:10 ` Mark Lord
2007-11-20 18:42 ` Mark Lord
2007-11-20 22:01 ` Ingo Molnar
2007-11-20 23:22 ` Mark Lord
2007-11-20 23:27 ` Ingo Molnar
2007-11-20 23:33 ` H. Peter Anvin
2007-11-20 23:47 ` Ingo Molnar
2007-11-20 23:50 ` H. Peter Anvin
2007-11-21 0:07 ` Ingo Molnar
2007-11-21 0:20 ` H. Peter Anvin
2007-11-21 0:36 ` Ingo Molnar
2007-11-21 0:47 ` H. Peter Anvin
2007-11-21 2:48 ` Jeff Garzik
2007-11-21 2:59 ` H. Peter Anvin
2007-11-20 23:28 ` H. Peter Anvin
2007-11-20 19:17 ` Andi Kleen
2007-11-21 2:22 Walt H
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