From: Oleg Nesterov <oleg@redhat.com>
To: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Roland McGrath <roland@redhat.com>,
caiqian@redhat.com, Heiko Carstens <heiko.carstens@de.ibm.com>,
Jan Kratochvil <jkratoch@redhat.com>,
linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
utrace-devel@redhat.com
Subject: Re: s390 && user_enable_single_step() (Was: odd utrace testing results on s390x)
Date: Thu, 21 Jan 2010 21:32:07 +0100 [thread overview]
Message-ID: <20100121203207.GA20050@redhat.com> (raw)
In-Reply-To: <20100107100050.31724463@mschwide.boeblingen.de.ibm.com>
On 01/07, Martin Schwidefsky wrote:
>
> On Wed, 6 Jan 2010 12:56:33 -0800 (PST)
> Roland McGrath <roland@redhat.com> wrote:
>
> > In other circumstances with utrace, it is very possible to wind up with
> > user_disable_single_step being called superfluously when there was no
> > stop (and so not necessarily any context switch or other high overhead).
> > On other machines, user_disable_single_step is pretty cheap even where
> > user_enable_single_step is quite costly. Given how simple and cheap it
> > is to short-circuit the excess work on s390, I think it is worthwhile.
>
> We could use the same compare of the control registers as the code in
> __switch_to. See below.
FYI, I tested your c3311c13adc1021e986fef12609ceb395ffc5014 commit which
does this optimization (compared to the patch you sent previously), it
works fine.
But please see another email I am going to send...
Oleg.
next prev parent reply other threads:[~2010-01-21 20:32 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1503844142.2061111261478093776.JavaMail.root@zmail06.collab.prod.int.phx2.redhat.com>
[not found] ` <1257887498.2061171261478252049.JavaMail.root@zmail06.collab.prod.int.phx2.redhat.com>
2010-01-04 15:52 ` s390 && user_enable_single_step() (Was: odd utrace testing results on s390x) Oleg Nesterov
2010-01-04 16:16 ` Martin Schwidefsky
2010-01-04 18:14 ` Oleg Nesterov
2010-01-04 19:30 ` Oleg Nesterov
2010-01-04 21:11 ` Roland McGrath
2010-01-05 9:50 ` Martin Schwidefsky
2010-01-05 15:36 ` Oleg Nesterov
2010-01-05 15:46 ` Martin Schwidefsky
2010-01-05 15:59 ` Oleg Nesterov
2010-01-05 17:03 ` Oleg Nesterov
2010-01-05 19:58 ` Oleg Nesterov
2010-01-06 14:59 ` Heiko Carstens
2010-01-06 20:17 ` Oleg Nesterov
2010-01-06 21:13 ` Roland McGrath
2010-01-07 9:18 ` Martin Schwidefsky
2010-01-07 17:54 ` Oleg Nesterov
2010-01-07 21:48 ` Roland McGrath
2010-01-21 20:51 ` Oleg Nesterov
2010-01-26 13:13 ` Martin Schwidefsky
2010-01-07 21:46 ` Roland McGrath
2010-01-08 8:30 ` Martin Schwidefsky
2010-01-08 10:25 ` Roland McGrath
2010-01-05 15:47 ` Oleg Nesterov
2010-01-05 15:50 ` Martin Schwidefsky
2010-01-06 21:08 ` Roland McGrath
2010-01-07 9:16 ` Martin Schwidefsky
2010-01-07 18:16 ` Oleg Nesterov
2010-01-07 21:44 ` Roland McGrath
2010-01-08 8:34 ` Martin Schwidefsky
2010-01-07 21:41 ` Roland McGrath
2010-01-07 18:11 ` Oleg Nesterov
2010-01-06 20:23 ` Oleg Nesterov
2010-01-06 20:56 ` Roland McGrath
2010-01-07 9:00 ` Martin Schwidefsky
2010-01-07 21:32 ` Roland McGrath
2010-01-21 20:32 ` Oleg Nesterov [this message]
2010-01-05 9:26 ` Martin Schwidefsky
2010-01-06 21:15 ` Roland McGrath
2010-01-04 20:46 ` Roland McGrath
[not found] <1158952983.251101262791902387.JavaMail.root@zmail06.collab.prod.int.phx2.redhat.com>
2010-01-06 15:33 ` caiqian
2010-01-06 20:09 ` Oleg Nesterov
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