From: Anthony Iliopoulos <anthony.iliopoulos@huawei.com>
To: Oren Twaig <oren@scalemp.com>
Cc: Dave Hansen <dave@sr71.net>, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Shay Goikhman <shay.goikhman@huawei.com>,
Paul Mundt <paul.mundt@huawei.com>,
Carlos Villavieja <villavieja@hps.utexas.edu>,
Nacho Navarro <nacho.navarro@bsc.es>,
Avi Mendelson <avi.mendelson@tce.technion.ac.il>,
Yoav Etsion <yetsion@tce.technion.ac.il>,
Gerald Schaefer <gerald.schaefer@de.ibm.com>,
David Gibson <david@gibson.dropbear.id.au>,
linux-arch <linux-arch@vger.kernel.org>
Subject: Re: [PATCH] x86, hugetlb: add missing TLB page invalidation for hugetlb_cow()
Date: Sat, 17 May 2014 11:24:14 +0200 [thread overview]
Message-ID: <20140517092355.GA38103@server-36.huawei.corp> (raw)
In-Reply-To: <53746721.6060408@scalemp.com>
Hi Oren,
On Thu, May 15, 2014 at 10:05:05AM +0300, Oren Twaig wrote:
>
> On 05/15/2014 08:00 PM, Anthony Iliopoulos wrote:
> > I have dismissed this case, since I assume that there are many more
> > cycles spent in servicing the TLB invalidation IPI, walking the pgtable
> > plus other related overhead (e.g. sched) than in updating the pte/pmd
> > so I am not sure how possible it would be to hit this condition.
>
> Hi Anthony,
>
> I have a question about the above statement. What will happen with multi
> cpu VMs ? won't the race described above can happen ? I.e one virtual CPU
> can will visit the host and the other will continue to encounter your race ?
I don't think there will be any race for the vcpu cases, since the sptes
will be cleared via the mmu_notifier, so this should take care of it
in the same manner as ptep_get_and_clear() does, as described by Dave
earlier in this thread.
Regards,
Anthony
WARNING: multiple messages have this Message-ID (diff)
From: Anthony Iliopoulos <anthony.iliopoulos@huawei.com>
To: Oren Twaig <oren@scalemp.com>
Cc: Dave Hansen <dave@sr71.net>, Thomas Gleixner <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>, <x86@kernel.org>,
<linux-kernel@vger.kernel.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Shay Goikhman <shay.goikhman@huawei.com>,
Paul Mundt <paul.mundt@huawei.com>,
Carlos Villavieja <villavieja@hps.utexas.edu>,
Nacho Navarro <nacho.navarro@bsc.es>,
"Avi Mendelson" <avi.mendelson@tce.technion.ac.il>,
Yoav Etsion <yetsion@tce.technion.ac.il>,
Gerald Schaefer <gerald.schaefer@de.ibm.com>,
David Gibson <david@gibson.dropbear.id.au>,
linux-arch <linux-arch@vger.kernel.org>
Subject: Re: [PATCH] x86, hugetlb: add missing TLB page invalidation for hugetlb_cow()
Date: Sat, 17 May 2014 11:24:14 +0200 [thread overview]
Message-ID: <20140517092355.GA38103@server-36.huawei.corp> (raw)
In-Reply-To: <53746721.6060408@scalemp.com>
Hi Oren,
On Thu, May 15, 2014 at 10:05:05AM +0300, Oren Twaig wrote:
>
> On 05/15/2014 08:00 PM, Anthony Iliopoulos wrote:
> > I have dismissed this case, since I assume that there are many more
> > cycles spent in servicing the TLB invalidation IPI, walking the pgtable
> > plus other related overhead (e.g. sched) than in updating the pte/pmd
> > so I am not sure how possible it would be to hit this condition.
>
> Hi Anthony,
>
> I have a question about the above statement. What will happen with multi
> cpu VMs ? won't the race described above can happen ? I.e one virtual CPU
> can will visit the host and the other will continue to encounter your race ?
I don't think there will be any race for the vcpu cases, since the sptes
will be cleared via the mmu_notifier, so this should take care of it
in the same manner as ptep_get_and_clear() does, as described by Dave
earlier in this thread.
Regards,
Anthony
next prev parent reply other threads:[~2014-05-17 9:25 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-14 9:29 [PATCH] x86, hugetlb: add missing TLB page invalidation for hugetlb_cow() Anthony Iliopoulos
2014-05-13 22:44 ` Dave Hansen
2014-05-15 17:00 ` Anthony Iliopoulos
2014-05-15 17:00 ` Anthony Iliopoulos
2014-05-14 17:24 ` Dave Hansen
2014-05-15 7:05 ` Oren Twaig
2014-05-17 9:24 ` Anthony Iliopoulos [this message]
2014-05-17 9:24 ` Anthony Iliopoulos
2014-05-13 23:36 ` [tip:x86/urgent] x86, mm, hugetlb: Add " tip-bot for Anthony Iliopoulos
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