From: Daniel Jacobowitz <dan@debian.org>
To: Renzo Davoli <renzo@cs.unibo.it>
Cc: Ulrich Drepper <drepper@gmail.com>, Andi Kleen <ak@suse.de>,
osd@cs.unibo.it, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] 2-ptrace_multi
Date: Fri, 19 May 2006 09:09:52 -0400 [thread overview]
Message-ID: <20060519130952.GA1242@nevyn.them.org> (raw)
In-Reply-To: <20060519090726.GA11789@cs.unibo.it>
On Fri, May 19, 2006 at 11:07:26AM +0200, Renzo Davoli wrote:
> On Thu, May 18, 2006 at 07:23:13PM -0700, Ulrich Drepper wrote:
> > On 5/18/06, Renzo Davoli <renzo@cs.unibo.it> wrote:
> > >e.g. To virtualize a write you'd have to call PTRACE_PEEKDATA for each
> > >word of the buffer, very many hundreds cycles lost.
> >
> > No, this is not how programs should do it. Just open /proc/PID/mem
> > and use pread() with an offset corresponding to the address. Now,
> > repeat your timings using this technique.
>
> That would be faster to access the memory but:
> - the manager has to keep one open file per controlled process
No, it doesn't. It can open it as needed. It can even maintain a
cache of open mem files.
GDB's been opening it as needed for years. It works very well and is
drastically faster than PTRACE_PEEKDATA.
--
Daniel Jacobowitz
CodeSourcery
next prev parent reply other threads:[~2006-05-19 13:09 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 [this message]
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
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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