From: Paolo Bonzini <pbonzini@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Fernando Luis Vazquez Cao <fernando_b1@lab.ntt.co.jp>,
Gleb Natapov <gleb@kernel.org>, Will Auld <will.auld@intel.com>,
qemu-devel@nongnu.org, kvm@vger.kernel.org
Subject: Re: [PATCH] target-i386: clear guest TSC on reset
Date: Thu, 05 Dec 2013 17:38:33 +0100 [thread overview]
Message-ID: <52A0AC09.4090202@redhat.com> (raw)
In-Reply-To: <20131205161707.GB17277@amt.cnet>
Il 05/12/2013 17:17, Marcelo Tosatti ha scritto:
>> > I agree it is a bit ugly, but in my testing QEMU seemed to loop over all
>> > the VCPUS fast enough for the kernel side kvm_write_tsc() to do a
>> > reasonable job of matching the offsets (the Linux guest did not mark
>> > the TSC unstable due to the TSCs being unsynchronized). Am I missing
>> > something?
> Right, modern kernels (see kvm_write_tsc) perform synchronization, so in
> theory the "KVM is yet unable to synchronize ..." code is not necessary
> anymore.
>
> I vote for dropping the thing entirely.
If it can be dropped entirely, I certainly have no problem with starting
with a simple patch first.
Paolo
WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>, Will Auld <will.auld@intel.com>,
qemu-devel@nongnu.org, kvm@vger.kernel.org,
Fernando Luis Vazquez Cao <fernando_b1@lab.ntt.co.jp>
Subject: Re: [Qemu-devel] [PATCH] target-i386: clear guest TSC on reset
Date: Thu, 05 Dec 2013 17:38:33 +0100 [thread overview]
Message-ID: <52A0AC09.4090202@redhat.com> (raw)
In-Reply-To: <20131205161707.GB17277@amt.cnet>
Il 05/12/2013 17:17, Marcelo Tosatti ha scritto:
>> > I agree it is a bit ugly, but in my testing QEMU seemed to loop over all
>> > the VCPUS fast enough for the kernel side kvm_write_tsc() to do a
>> > reasonable job of matching the offsets (the Linux guest did not mark
>> > the TSC unstable due to the TSCs being unsynchronized). Am I missing
>> > something?
> Right, modern kernels (see kvm_write_tsc) perform synchronization, so in
> theory the "KVM is yet unable to synchronize ..." code is not necessary
> anymore.
>
> I vote for dropping the thing entirely.
If it can be dropped entirely, I certainly have no problem with starting
with a simple patch first.
Paolo
next prev parent reply other threads:[~2013-12-05 16:38 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-03 7:08 [PATCH] kvm: clear guest TSC on reset Fernando Luis Vázquez Cao
2013-12-03 8:04 ` Fernando Luis Vázquez Cao
2013-12-05 6:08 ` Fernando Luis Vázquez Cao
2013-12-05 6:08 ` [Qemu-devel] " Fernando Luis Vázquez Cao
2013-12-05 6:15 ` [PATCH] target-i386: " Fernando Luis Vázquez Cao
2013-12-05 6:15 ` [Qemu-devel] " Fernando Luis Vázquez Cao
2013-12-05 9:28 ` Paolo Bonzini
2013-12-05 9:28 ` [Qemu-devel] " Paolo Bonzini
2013-12-05 13:15 ` Fernando Luis Vazquez Cao
2013-12-05 13:15 ` [Qemu-devel] " Fernando Luis Vazquez Cao
2013-12-05 13:53 ` Paolo Bonzini
2013-12-05 13:53 ` [Qemu-devel] " Paolo Bonzini
2013-12-05 15:42 ` Fernando Luis Vazquez Cao
2013-12-05 15:42 ` [Qemu-devel] " Fernando Luis Vazquez Cao
2013-12-05 16:02 ` Paolo Bonzini
2013-12-05 16:02 ` [Qemu-devel] " Paolo Bonzini
2013-12-05 16:40 ` Marcelo Tosatti
2013-12-05 16:40 ` [Qemu-devel] " Marcelo Tosatti
2013-12-05 17:06 ` Marcelo Tosatti
2013-12-05 17:06 ` [Qemu-devel] " Marcelo Tosatti
2013-12-05 16:17 ` Marcelo Tosatti
2013-12-05 16:17 ` [Qemu-devel] " Marcelo Tosatti
2013-12-05 16:38 ` Paolo Bonzini [this message]
2013-12-05 16:38 ` Paolo Bonzini
2013-12-06 8:24 ` Fernando Luis Vázquez Cao
2013-12-06 8:24 ` [Qemu-devel] " Fernando Luis Vázquez Cao
2013-12-06 8:33 ` [PATCH 1//2 v3] " Fernando Luis Vázquez Cao
2013-12-06 8:33 ` [Qemu-devel] " Fernando Luis Vázquez Cao
2013-12-06 8:38 ` [PATCH 2/2] target-i386: do not special case TSC writeback Fernando Luis Vázquez Cao
2013-12-06 8:38 ` [Qemu-devel] " Fernando Luis Vázquez Cao
2013-12-06 8:36 ` [PATCH] target-i386: clear guest TSC on reset Paolo Bonzini
2013-12-06 8:36 ` [Qemu-devel] " Paolo Bonzini
2013-12-06 8:56 ` Fernando Luis Vázquez Cao
2013-12-06 8:56 ` [Qemu-devel] " Fernando Luis Vázquez Cao
2013-12-06 9:08 ` Paolo Bonzini
2013-12-06 9:08 ` [Qemu-devel] " Paolo Bonzini
2013-12-06 9:20 ` Fernando Luis Vazquez Cao
2013-12-06 9:20 ` [Qemu-devel] " Fernando Luis Vazquez Cao
2013-12-06 14:22 ` Marcelo Tosatti
2013-12-06 14:22 ` [Qemu-devel] " Marcelo Tosatti
2013-12-09 8:50 ` Fernando Luis Vázquez Cao
2013-12-09 8:50 ` [Qemu-devel] " Fernando Luis Vázquez Cao
2013-12-12 2:52 ` Fernando Luis Vázquez Cao
2013-12-12 2:52 ` [Qemu-devel] " Fernando Luis Vázquez Cao
2013-12-12 12:18 ` Paolo Bonzini
2013-12-12 12:18 ` [Qemu-devel] " Paolo Bonzini
2013-12-05 16:12 ` Marcelo Tosatti
2013-12-05 16:12 ` [Qemu-devel] " Marcelo Tosatti
2013-12-05 16:32 ` Paolo Bonzini
2013-12-05 16:32 ` [Qemu-devel] " Paolo Bonzini
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