From: Marcelo Tosatti <mtosatti@redhat.com>
To: Oscar Garcia <oscar@softlab.cs.tsukuba.ac.jp>
Cc: kvm@vger.kernel.org
Subject: Re: VMEXIT and Threads
Date: Mon, 6 Oct 2014 16:07:16 -0300 [thread overview]
Message-ID: <20141006190716.GA5731@amt.cnet> (raw)
In-Reply-To: <54321E64.8070306@softlab.cs.tsukuba.ac.jp>
On Mon, Oct 06, 2014 at 01:45:24PM +0900, Oscar Garcia wrote:
> Hello,
>
> I have a question about parallel vmexit calls, I would appreciate
> any answer or suggestion.
>
> I have a host with debian 7 (intel i7 - RAM 8GB), the guest OS is
> also debian. I am running a program with some threads, every thread
> makes a vmexit call.
How is that vmexit call made?
> Also every thread runs in a isolated vcpu. The
> problem is that the program does not run fluently, it looks like
> that every thread interfere with each other.
Can you be more precise about this? Did you perform a measurement?
> This situation does not happen when separately processes call vmexit
> simultaneously. The question is: there is any restriction (any lock)
> that block the threads. I am not sure maybe libc, RCU, on even Qemu
> and KVM?
In QEMU there is a mutex which is shared by all vcpus, and is acquired
right after entry in QEMU, named qemu_mutex.
prev parent reply other threads:[~2014-10-06 19:07 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-06 4:45 VMEXIT and Threads Oscar Garcia
2014-10-06 6:51 ` Paolo Bonzini
2014-10-06 7:29 ` Jan Kiszka
2014-10-06 19:07 ` Marcelo Tosatti [this message]
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