From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org,
kvm-ppc@vger.kernel.org, Vaibhav Jain <vaibhav@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Jordan Niethe <jniethe5@gmail.com>,
Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>,
mikey@neuling.org, paulus@ozlabs.org, sbhat@linux.ibm.com,
gautam@linux.ibm.com, kconsul@linux.vnet.ibm.com,
amachhiw@linux.vnet.ibm.com, David.Laight@ACULAB.COM
Subject: Re: [PATCH v2] KVM: PPC: Book3S HV nestedv2: Cancel pending DEC exception
Date: Wed, 08 May 2024 23:45:54 +1000 [thread overview]
Message-ID: <171517595456.167543.8572230162605343190.b4-ty@ellerman.id.au> (raw)
In-Reply-To: <20240415035731.103097-1-vaibhav@linux.ibm.com>
On Mon, 15 Apr 2024 09:27:29 +0530, Vaibhav Jain wrote:
> This reverts commit 180c6b072bf3 ("KVM: PPC: Book3S HV nestedv2: Do not
> cancel pending decrementer exception") [1] which prevented canceling a
> pending HDEC exception for nestedv2 KVM guests. It was done to avoid
> overhead of a H_GUEST_GET_STATE hcall to read the 'DEC expiry TB' register
> which was higher compared to handling extra decrementer exceptions.
>
> However recent benchmarks indicate that overhead of not handling 'DECR'
> expiry for Nested KVM Guest(L2) is higher and results in much larger exits
> to Pseries Host(L1) as indicated by the Unixbench-arithoh bench[2]
>
> [...]
Applied to powerpc/topic/ppc-kvm.
[1/1] KVM: PPC: Book3S HV nestedv2: Cancel pending DEC exception
https://git.kernel.org/powerpc/c/7be6ce7043b4cf293c8826a48fd9f56931cef2cf
cheers
prev parent reply other threads:[~2024-05-08 13:46 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-15 3:57 [PATCH v2] KVM: PPC: Book3S HV nestedv2: Cancel pending DEC exception Vaibhav Jain
2024-04-15 12:27 ` Michael Ellerman
2024-05-08 13:45 ` Michael Ellerman [this message]
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