From: Ingo Molnar <mingo@elte.hu>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>, kvm <kvm@vger.kernel.org>,
Asias He <asias.hejun@gmail.com>,
qemu-devel <qemu-devel@nongnu.org>,
Pekka Enberg <penberg@cs.helsinki.fi>,
Sasha Levin <levinsasha928@gmail.com>,
Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [Qemu-devel] [RFC][PATCH] Register Linux dyntick timer as per-thread signal
Date: Thu, 16 Jun 2011 12:26:06 +0200 [thread overview]
Message-ID: <20110616102606.GA24541@elte.hu> (raw)
In-Reply-To: <4DF9CD7E.5020509@siemens.com>
* Jan Kiszka <jan.kiszka@siemens.com> wrote:
> Ingo Molnar pointed out that sending the timer signal to the whole
> process, just blocking it everywhere, is suboptimal with an increasing
> number of threads. QEMU is using this pattern so far.
>
> But Linux provides a (non-portable) way to restrict the signal to a
> single thread: Use SIGEV_THREAD_ID unless we are forced to emulate
> signalfd via an additional thread. That case could theoretically be
> optimized as well, but it doesn't look worth bothering.
Would be nice to mention it in the changelog that the context and
motivation for my remark was a patch sent for tools/kvm/ by Asias He:
kvm tools: Block SIGALRM for vcpu thread using sig_block() helper
Thanks,
Ingo
next prev parent reply other threads:[~2011-06-16 13:57 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-16 9:31 [Qemu-devel] [RFC][PATCH] Register Linux dyntick timer as per-thread signal Jan Kiszka
2011-06-16 10:26 ` Ingo Molnar [this message]
2011-06-16 14:39 ` Richard Henderson
2011-06-16 15:24 ` Alexandre Raymond
2011-06-17 9:25 ` Jan Kiszka
2011-06-17 9:25 ` [Qemu-devel] [PATCH v2] " Jan Kiszka
2011-06-17 18:06 ` Richard Henderson
2011-07-23 16:52 ` Anthony Liguori
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