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From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>, Wei Liu <wl@xen.org>
Subject: Re: [PATCH v4 2/3] x86/time: yield to hyperthreads after updating TSC during rendezvous
Date: Tue, 20 Apr 2021 17:59:00 +0200	[thread overview]
Message-ID: <YH76RJTqvwYmvXu+@Air-de-Roger> (raw)
In-Reply-To: <81da85eb-2e8e-9b76-2fb3-2beddc33e9af@suse.com>

On Thu, Apr 01, 2021 at 11:54:27AM +0200, Jan Beulich wrote:
> Since we'd like the updates to be done as synchronously as possible,
> make an attempt at yielding immediately after the TSC write.
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>

Did you observe any difference with the pause inserted?

I wonder whether that's enough to give a chance the hyperthread to
also perform the TSC write. In any case there's no harm from it
certainly.

Thanks, Roger.


  reply	other threads:[~2021-04-20 15:59 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-01  9:53 [PATCH v4 0/3] x86/time: calibration rendezvous adjustments Jan Beulich
2021-04-01  9:54 ` [PATCH v4 1/3] x86/time: latch to-be-written TSC value early in rendezvous loop Jan Beulich
2021-04-20 15:44   ` Roger Pau Monné
2021-04-01  9:54 ` [PATCH v4 2/3] x86/time: yield to hyperthreads after updating TSC during rendezvous Jan Beulich
2021-04-20 15:59   ` Roger Pau Monné [this message]
2021-04-21  9:57     ` Jan Beulich
2021-04-01  9:55 ` [PATCH v4 3/3] x86/time: avoid reading the platform timer in rendezvous functions Jan Beulich
2021-04-20 16:12   ` Roger Pau Monné
2021-04-21 10:06     ` Jan Beulich
2021-04-29  9:32       ` Jan Beulich
2021-04-29 12:48       ` Roger Pau Monné
2021-04-29 12:53   ` Roger Pau Monné
2021-04-29 13:51     ` Jan Beulich
2021-04-15  9:54 ` Ping: [PATCH v4 0/3] x86/time: calibration rendezvous adjustments Jan Beulich

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