From: Jeff Dike <jdike@addtoit.com>
To: Renzo Davoli <renzo@cs.unibo.it>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>, Andi Kleen <ak@suse.de>,
Daniel Jacobowitz <dan@debian.org>,
Ulrich Drepper <drepper@gmail.com>,
osd@cs.unibo.it, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] 2-ptrace_multi
Date: Sat, 20 May 2006 17:39:59 -0400 [thread overview]
Message-ID: <20060520213959.GA4229@ccure.user-mode-linux.org> (raw)
In-Reply-To: <20060520183020.GC11648@cs.unibo.it>
On Sat, May 20, 2006 at 08:30:20PM +0200, Renzo Davoli wrote:
> Let me point out that PTRACE_MULTI is not only related to memory access.
> We are using PTRACE_MULTI also to store the registers and restart the
> execution of the ptraced process with a single syscall.
> This is very effective when umview runs on a ppc32 architecture. In
> fact, PPC_PTRACE_{G,S}ETREGS do not exist for that architecture
> (IMHO there is no evident reason for that). Without PTRACE_MULTI each register
> must be read/written individually by a PTRACE_{PEEK,POKE}USER(*)
Wouldn't the obvious fix be to implement [GS]ETREGS for arches that don't
have them?
> PTRACE_MULTI can be also used to optimize many other virtualized calls,
> e.g. to read/write all the buffers for a readv/writev/recvmsg/sendmsg
> call at once.
Here, I bet the data copying cost dominates the system call, and the
syscall overhead is minimal.
Jeff
next prev parent reply other threads:[~2006-05-20 21:42 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-18 15:53 ptrace enhancements for VM support (patch proposals follow in sep.msgs) Renzo Davoli
2006-05-18 15:56 ` [PATCH] 1-access_process_vm_user Renzo Davoli
2006-05-18 15:58 ` [PATCH] 2-ptrace_multi Renzo Davoli
2006-05-18 20:17 ` Andi Kleen
2006-05-18 21:13 ` Renzo Davoli
2006-05-19 2:23 ` Ulrich Drepper
2006-05-19 9:07 ` Renzo Davoli
2006-05-19 13:09 ` Daniel Jacobowitz
2006-05-19 17:45 ` Renzo Davoli
2006-05-19 19:15 ` Renzo Davoli
2006-05-19 20:15 ` Daniel Jacobowitz
2006-05-19 20:17 ` Andi Kleen
2006-05-20 6:44 ` Ulrich Drepper
2006-05-20 14:37 ` Alan Cox
2006-05-20 18:30 ` Renzo Davoli
2006-05-20 20:23 ` Ulrich Drepper
2006-05-20 21:39 ` Jeff Dike [this message]
2006-05-21 12:38 ` Avi Kivity
2006-05-21 15:28 ` Renzo Davoli
2006-05-22 13:02 ` Daniel Jacobowitz
2006-05-22 15:05 ` Renzo Davoli
2006-05-22 15:26 ` Daniel Jacobowitz
2006-05-18 16:07 ` [PATCH] 3-ptrace_vm Renzo Davoli
2006-05-21 8:03 ` ptrace enhancements for VM support (patch proposals follow in sep.msgs) Peter Chubb
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