From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
benh@kernel.crashing.org, paulus@samba.org
Cc: linuxppc-dev@lists.ozlabs.org,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Subject: Re: [v3,2/3] powerpc/mm: Don't send IPI to all cpus on THP updates
Date: Mon, 21 Aug 2017 23:39:09 +1000 (AEST) [thread overview]
Message-ID: <3xbZXs5CkYz9sDB@ozlabs.org> (raw)
In-Reply-To: <20170727062455.15404-2-aneesh.kumar@linux.vnet.ibm.com>
On Thu, 2017-07-27 at 06:24:54 UTC, "Aneesh Kumar K.V" wrote:
> Now that we made sure that lockless walk of linux page table is mostly limitted
> to current task(current->mm->pgdir) we can update the THP update sequence to
> only send IPI to cpus on which this task has run. This helps in reducing the IPI
> overload on systems with large number of CPUs.
>
> W.r.t kvm even though kvm is walking page table with vpc->arch.pgdir, it is
> done only on secondary cpus and in that case we have primary cpu added to
> task's mm cpumask. Sending an IPI to primary will force the secondary to do
> a vm exit and hence this mm cpumask usage is safe here.
>
> W.r.t CAPI, we still end up walking linux page table with capi context MM. For
> now the pte lookup serialization sends an IPI to all cpus in CPI is in use. We
> can further improve this by adding the CAPI interrupt handling cpu to task
> mm cpumask. That will be done in a later patch.
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/fa4531f753f1c80d21b5eb86ec5c02
cheers
next prev parent reply other threads:[~2017-08-21 13:39 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-27 6:24 [PATCH v3 1/3] powerpc/mm: Rename find_linux_pte_or_hugepte Aneesh Kumar K.V
2017-07-27 6:24 ` [PATCH v3 2/3] powerpc/mm: Don't send IPI to all cpus on THP updates Aneesh Kumar K.V
2017-08-21 13:39 ` Michael Ellerman [this message]
2017-07-27 6:24 ` [PATCH v3 3/3] powerpc/mm/cxl: Add the fault handling cpu to mm cpumask Aneesh Kumar K.V
2017-08-21 13:39 ` [v3, " Michael Ellerman
2017-08-21 16:49 ` [v3,3/3] " Benjamin Herrenschmidt
2017-08-21 13:39 ` [v3,1/3] powerpc/mm: Rename find_linux_pte_or_hugepte Michael Ellerman
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