From: Eduardo Habkost <ehabkost@redhat.com>
To: Babu Moger <babu.moger@amd.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Ani Sinha <ani.sinha@nutanix.com>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"Singh, Brijesh" <brijesh.singh@amd.com>,
"rth@twiddle.net" <rth@twiddle.net>
Subject: Re: [PATCH] i386: pass CLZERO to guests with EPYC CPU model on AMD ZEN platform
Date: Thu, 6 Feb 2020 11:03:08 -0500 [thread overview]
Message-ID: <20200206160308.GB25446@habkost.net> (raw)
In-Reply-To: <78f5dad9-5433-3f7c-69cb-db496b1c37a7@amd.com>
On Thu, Feb 06, 2020 at 09:30:11AM -0600, Babu Moger wrote:
>
>
> On 2/5/20 11:53 PM, Ani Sinha wrote:
> >
> >
> >> On Feb 6, 2020, at 11:16 AM, Ani Sinha <ani.sinha@nutanix.com> wrote:
> >>
> >>
> >>
> >>> On Feb 6, 2020, at 5:30 AM, Moger, Babu <Babu.Moger@amd.com> wrote:
> >>>
> >>> Ani, I am already working on it.
> >>
> >> Wow, I see a whole new AMD-Rome CPU model with it’s own cache info data :
> >>
> >> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fqemu-devel%2F157314966312.23828.17684821666338093910.stgit%40naples-babu.amd.com%2F&data=02%7C01%7CBabu.Moger%40amd.com%7Cc566dc5cf3cc407b5ee608d7aac8d9bc%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637165651955089264&sdata=tlafWD6m5%2BZ12cqd4vqJcWh0%2FIgly%2FPVMgAbjxK5Mog%3D&reserved=0
> >
> > Do you think the ROME specific guest cpu cache data will have significant impact on performance?
>
> I have not done performance benchmarks myself. Yes. Rome is expected to
> perform better than its previous generations.
Note that virtual cache information on CPUID doesn't affect host
software or hardware behavior in any way. In the exceptional
cases it affects performance, it's solely because guest software
behavior changed depending on the cache information it sees.
--
Eduardo
next prev parent reply other threads:[~2020-02-06 16:04 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-18 9:05 [PATCH] i386: pass CLZERO to guests with EPYC CPU model on AMD ZEN platform Ani Sinha
2019-12-18 11:53 ` Paolo Bonzini
2019-12-18 15:11 ` Eduardo Habkost
2020-01-20 10:56 ` Ani Sinha
2020-02-05 22:37 ` Eduardo Habkost
2020-02-06 0:00 ` Moger, Babu
2020-02-06 5:46 ` Ani Sinha
2020-02-06 5:53 ` Ani Sinha
2020-02-06 15:30 ` Babu Moger
2020-02-06 16:03 ` Eduardo Habkost [this message]
2020-02-06 15:52 ` Eduardo Habkost
2020-02-06 15:55 ` Babu Moger
2019-12-22 7:32 ` Ani Sinha
2019-12-22 8:15 ` Paolo Bonzini
2019-12-23 8:14 ` Ani Sinha
2019-12-23 8:50 ` Ani Sinha
[not found] <yes>
2019-12-04 9:36 ` Ani Sinha
2019-12-16 9:31 ` Ani Sinha
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