From: Jeff Dike <jdike@karaya.com>
To: Andrea Arcangeli <andrea@suse.de>
Cc: Andi Kleen <ak@muc.de>, john stultz <johnstul@us.ibm.com>,
Linus Torvalds <torvalds@transmeta.com>,
lkml <linux-kernel@vger.kernel.org>,
george anzinger <george@mvista.com>,
Stephen Hemminger <shemminger@osdl.org>,
Bill Davidsen <davidsen@tmr.com>
Subject: Re: [PATCH] linux-2.5.43_vsyscall_A0
Date: Tue, 22 Oct 2002 00:07:16 -0500 [thread overview]
Message-ID: <200210220507.AAA06089@ccure.karaya.com> (raw)
In-Reply-To: Your message of "Sun, 20 Oct 2002 04:33:21 +0200." <20021020023321.GS23930@dualathlon.random>
andrea@suse.de said:
> yes, this is true for all the syscalls, if that's a problem uml isn't
> an option for the user in the first place.
Not true. Any marginal increase in performance will make a number of
applications fast enough that they become practical in UML. Since there
are apps which, to a first order approximation, do nothing but call
gettimeofday, they are not usable in UML today, but could become usable if
UML had vgettimeofday. I've had complaints about this, so the need is
definitely there.
> what do you plan to do to make all other syscall faster?
Right now, a UML syscall involves four host context switches and a host
signal delivery and return. I'm merging some changes which will reduce
that to two host context switches and no signals. Once that's done, I'm
going to look for more improvements.
> My problem is that mapping user code into the vsyscall fixmap is
> complex and not very clean at all, breaks various concepts in the mm
> and last but not the least it is slow
Can you explain, in small words, why mapping user code is so horrible?
Jeff
next prev parent reply other threads:[~2002-10-22 3:57 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-10-18 22:57 [PATCH] linux-2.5.43_vsyscall_A0 john stultz
2002-10-18 22:58 ` [EXAMPLE CODE] linux-2.5.43_vsyscall_A0 john stultz
2002-10-19 3:52 ` [PATCH] linux-2.5.43_vsyscall_A0 Jeff Dike
2002-10-19 3:10 ` Andi Kleen
2002-10-19 4:49 ` Jeff Dike
2002-10-19 4:02 ` Andi Kleen
2002-10-19 4:16 ` Andrea Arcangeli
2002-10-20 2:59 ` Andi Kleen
2002-10-20 6:44 ` Elladan
2002-10-20 9:27 ` [discuss] " Andi Kleen
2002-10-20 10:58 ` Elladan
2002-10-20 11:20 ` Andi Kleen
2002-10-20 14:51 ` Andrea Arcangeli
2002-10-21 16:49 ` george anzinger
2002-10-20 13:19 ` Andreas Jaeger
2002-10-20 14:59 ` Andrea Arcangeli
2002-10-19 4:10 ` Andrea Arcangeli
2002-10-19 4:45 ` Andi Kleen
2002-10-19 5:01 ` Andrea Arcangeli
2002-10-19 23:43 ` Jeff Dike
2002-10-20 0:15 ` Andrea Arcangeli
2002-10-20 2:03 ` Jeff Dike
2002-10-20 2:33 ` Andrea Arcangeli
2002-10-22 5:07 ` Jeff Dike [this message]
2002-10-22 4:15 ` Andi Kleen
2002-10-22 4:29 ` Andrew Morton
2002-10-22 9:39 ` Alan Cox
2002-10-22 16:12 ` Andrew Morton
2002-10-22 5:08 ` Andrea Arcangeli
2002-10-22 5:27 ` Andrea Arcangeli
2002-10-22 7:24 ` Elladan
2002-10-22 7:40 ` Andrea Arcangeli
2002-10-23 5:12 ` Elladan
2002-10-23 5:43 ` Elladan
2002-10-23 17:51 ` Gerrit Huizenga
2002-10-21 15:43 ` Stephen Hemminger
2002-10-21 16:26 ` Andi Kleen
2002-10-21 17:10 ` john stultz
2002-10-19 19:14 ` Bill Davidsen
2002-10-20 1:50 ` Rik van Riel
2002-10-20 2:56 ` Andi Kleen
2002-10-24 11:24 ` Pavel Machek
2002-10-24 11:24 ` Pavel Machek
2002-10-19 22:36 ` Ton Hospel
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