From: "H. Peter Anvin" <hpa@zytor.com>
To: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: Pavel Machek <pavel@ucw.cz>,
mingo@elte.hu, akpm@osdl.org,
Jeremy Fitzhardinge <jeremy@goop.org>,
Steven Rostedt <rostedt@goodmis.org>,
"Frank Ch. Eigler" <fche@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] x86 NMI-safe INT3 and Page Fault (v5)
Date: Mon, 21 Apr 2008 13:59:27 -0400 [thread overview]
Message-ID: <480CD5FF.3050708@zytor.com> (raw)
In-Reply-To: <20080421174239.GA14718@Krystal>
Mathieu Desnoyers wrote:
> * H. Peter Anvin (hpa@zytor.com) wrote:
>> Pavel Machek wrote:
>>>> There is also the page fault case. I think putting this test in
>>>> ret_from_exception would be both safe (it is executed for any
>>>> exception return) and fast (exceptions are rare).
>>> Eh? I thought that page fault is one of the hottest paths in kernel
>>> (along with syscall and packet receive/send)...
>>> Pavel
>
> On x86_64, we can pinpoint only the page faults returning to the kernel,
> which are rare and only caused by vmalloc accesses. Ideally we could do
> the same on x86_32.
>
Pinpoint, how? Ultimately you need a runtime test, and you better be
showing that people are going to die unless before you add a cycle to
the page fault path. I'm only slightly exaggerating that.
-hpa
next prev parent reply other threads:[~2008-04-21 18:06 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20080417165839.GA25198@Krystal>
[not found] ` <20080417165944.GB25198@Krystal>
2008-04-17 20:14 ` [RFC PATCH] x86 NMI-safe INT3 and Page Fault (v5) Mathieu Desnoyers
2008-04-17 20:29 ` Andrew Morton
2008-04-17 21:16 ` Mathieu Desnoyers
2008-04-17 21:26 ` Andrew Morton
2008-04-17 22:01 ` Andi Kleen
2008-04-18 0:06 ` Mathieu Desnoyers
2008-04-18 8:07 ` Andi Kleen
2008-04-19 21:00 ` Mathieu Desnoyers
2008-04-18 11:30 ` Andi Kleen
2008-04-19 21:23 ` Mathieu Desnoyers
2008-04-21 14:00 ` Pavel Machek
2008-04-21 14:22 ` H. Peter Anvin
2008-04-21 14:51 ` Mathieu Desnoyers
2008-04-21 15:08 ` Mathieu Desnoyers
2008-04-21 15:08 ` H. Peter Anvin
2008-04-21 15:21 ` Mathieu Desnoyers
2008-04-21 15:47 ` Mathieu Desnoyers
2008-04-21 17:23 ` Pavel Machek
2008-04-21 17:28 ` H. Peter Anvin
2008-04-21 17:42 ` Mathieu Desnoyers
2008-04-21 17:59 ` H. Peter Anvin [this message]
2008-04-22 13:12 ` Mathieu Desnoyers
2008-04-21 15:11 ` Mathieu Desnoyers
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