From: Jes Sorensen <jes@sgi.com>
To: "Zhang, Xiantao" <xiantao.zhang@intel.com>
Cc: Avi Kivity <avi@qumranet.com>, "Luck, Tony" <tony.luck@intel.com>,
"Xu, Anthony" <anthony.xu@intel.com>,
Akio Takebe <takebe_akio@jp.fujitsu.com>,
kvm-devel@lists.sourceforge.net,
kvm-ia64-devel@lists.sourceforge.net, linux-ia64@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Carsten Otte <cotte@de.ibm.com>
Subject: Re: [02/17][PATCH] Implement smp_call_function_mask for ia64 - V8
Date: Mon, 31 Mar 2008 11:12:56 +0200 [thread overview]
Message-ID: <47F0AB18.2010707@sgi.com> (raw)
In-Reply-To: <42DFA526FC41B1429CE7279EF83C6BDC01048240@pdsmsx415.ccr.corp.intel.com>
Zhang, Xiantao wrote:
>>From 697d50286088e98da5ac8653c80aaa96c81abf87 Mon Sep 17 00:00:00 2001
> From: Xiantao Zhang <xiantao.zhang@intel.com>
> Date: Mon, 31 Mar 2008 09:50:24 +0800
> Subject: [PATCH] KVM:IA64: Implement smp_call_function_mask for ia64
>
> This function provides more flexible interface for smp
> infrastructure.
> Signed-off-by: Xiantao Zhang <xiantao.zhang@intel.com>
Hi Xiantao,
I'm a little wary of the performance impact of this change. Doing a
cpumask compare on all smp_call_function calls seems a little expensive.
Maybe it's just noise in the big picture compared to the actual cost of
the IPIs, but I thought I'd bring it up.
Keep in mind that a cpumask can be fairly big these days, max NR_CPUS
is currently 4096. For those booting a kernel with NR_CPUS at 4096 on
a dual CPU machine, it would be a bit expensive.
Why not keep smp_call_function() the way it was before, rather than
implementing it via the call to smp_call_function_mask()?
Cheers,
Jes
next parent reply other threads:[~2008-03-31 9:12 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <42DFA526FC41B1429CE7279EF83C6BDC01048240@pdsmsx415.ccr.corp.intel.com>
2008-03-31 9:12 ` Jes Sorensen [this message]
2008-03-31 10:17 ` [kvm-devel] [02/17][PATCH] Implement smp_call_function_mask foria64 - V8 Zhang, Xiantao
2008-03-31 15:02 ` [02/17][PATCH] Implement smp_call_function_mask for ia64 " Jeremy Fitzhardinge
2008-04-01 8:34 ` Jes Sorensen
2008-04-01 16:06 ` Jeremy Fitzhardinge
2008-04-02 7:30 ` Jes Sorensen
2008-04-02 23:48 ` Luck, Tony
2008-03-31 8:25 Zhang, Xiantao
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