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From: Jan Beulich <jbeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: George Dunlap <george.dunlap@citrix.com>,
	Ian Jackson <iwj@xenproject.org>, Julien Grall <julien@xen.org>,
	Stefano Stabellini <sstabellini@kernel.org>, Wei Liu <wl@xen.org>,
	xen-devel@lists.xenproject.org,
	Dmitry Isaikin <isaikin-dmitry@yandex.ru>
Subject: Re: [PATCH v1] domctl: hold domctl lock while domain is destroyed
Date: Fri, 17 Sep 2021 08:17:02 +0200	[thread overview]
Message-ID: <f1dda72c-695f-34d3-619e-ec2aa7696bce@suse.com> (raw)
In-Reply-To: <16d43ba8-d45f-021c-0e19-e233cb967938@citrix.com>

On 16.09.2021 19:52, Andrew Cooper wrote:
> On 16/09/2021 13:30, Jan Beulich wrote:
>> On 16.09.2021 13:10, Dmitry Isaikin wrote:
>>> From: Dmitry Isaykin <isaikin-dmitry@yandex.ru>
>>>
>>> This significantly speeds up concurrent destruction of multiple domains on x86.
>> This effectively is a simplistic revert of 228ab9992ffb ("domctl:
>> improve locking during domain destruction"). There it was found to
>> actually improve things;
> 
> Was it?  I recall that it was simply an expectation that performance
> would be better...

My recollection is that it was, for one of our customers.

> Amazon previously identified 228ab9992ffb as a massive perf hit, too.

Interesting. I don't recall any mail to that effect.

> Clearly some of the reasoning behind 228ab9992ffb was flawed and/or
> incomplete, and it appears as if it wasn't necessarily a wise move in
> hindsight.

Possible; I continue to think though that the present observation wants
properly understanding instead of more or less blindly undoing that
change.

Jan



  reply	other threads:[~2021-09-17  6:17 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-16 11:10 Dmitry Isaikin
2021-09-16 12:30 ` Jan Beulich
2021-09-16 13:08   ` Roger Pau Monné
2021-09-16 17:52   ` Andrew Cooper
2021-09-17  6:17     ` Jan Beulich [this message]
2021-09-17  9:27       ` Julien Grall
2021-09-17  9:41         ` Andrew Cooper
2021-09-17  9:47           ` Jan Beulich
2021-09-17 16:01             ` Julien Grall
2021-09-20  8:19               ` Jan Beulich

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