From: Paul Mackerras <paulus@samba.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Greg KH <gregkh@suse.de>, Philip Mucci <mucci@cs.utk.edu>,
eranian@hpl.hp.com, William Cohen <wcohen@redhat.com>,
Robert Richter <robert.richter@amd.com>,
linux-kernel@vger.kernel.org, Andi Kleen <andi@firstfloor.org>
Subject: Re: [perfmon] Re: [perfmon2] perfmon2 merge news
Date: Wed, 14 Nov 2007 22:39:24 +1100 [thread overview]
Message-ID: <18234.56940.229831.735533@cargo.ozlabs.ibm.com> (raw)
In-Reply-To: <20071114110009.GA17833@infradead.org>
Christoph Hellwig writes:
> int pfm_read_pmds(int fd, pfarg_pmd_t *pmds, int n)
>
> This is basically a read(2) (or for other syscalls a write) on something
> else than the file descriptor provided to the system call.
No it's not basically a read(). It's more like a request/reply
interface, which a read()/write() interface doesn't handle very well.
The request in this case is "tell me about this particular collection
of PMDs" and the reply is the values.
It seems to me that an important part of this is to be able to collect
values from several PMDs at a single point in time, or at least an
approximation to a single point in time. So that means that you don't
want a file per PMD either.
Basically we don't have a good abstraction for a request/reply (or
command/response) type of interface, and this is a case where we need
one. Having a syscall that takes a struct containing the request and
reply is as good a way as any, particularly for something that needs
to be quick.
Paul.
next prev parent reply other threads:[~2007-11-14 11:45 UTC|newest]
Thread overview: 116+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-07 0:34 [PATCH] fix up perfmon to build on -mm Greg KH
2007-11-07 10:34 ` Stephane Eranian
2007-11-07 17:07 ` Greg KH
2007-11-07 13:42 ` Stephane Eranian
2007-11-07 17:08 ` Greg KH
2007-11-07 17:33 ` Andrew Morton
2007-11-07 17:41 ` Greg KH
2007-11-07 17:50 ` Stephane Eranian
2007-11-07 17:47 ` Greg KH
2007-11-07 17:57 ` Stephane Eranian
2007-11-07 19:53 ` Greg KH
2007-11-07 20:39 ` Stephane Eranian
2007-11-08 15:27 ` Stephane Eranian
2007-11-09 20:06 ` Andrew Morton
2007-11-09 21:38 ` Greg KH
2007-11-10 20:32 ` Andi Kleen
2007-11-13 15:17 ` perfmon2 merge news Robert Richter
2007-11-13 15:35 ` [perfmon2] " William Cohen
2007-11-13 17:55 ` Stephane Eranian
2007-11-13 18:33 ` [perfmon] " William Cohen
2007-11-13 21:13 ` Stephane Eranian
2007-11-13 21:29 ` Andi Kleen
2007-11-13 21:46 ` Stephane Eranian
2007-11-13 21:50 ` Andi Kleen
2007-11-13 22:22 ` Stephane Eranian
2007-11-13 22:25 ` Andi Kleen
2007-11-13 22:58 ` Stephane Eranian
2007-11-14 2:07 ` Andi Kleen
2007-11-14 13:09 ` Stephane Eranian
2007-11-14 14:24 ` Andi Kleen
2007-11-14 15:44 ` William Cohen
2007-11-14 16:13 ` Stephane Eranian
2007-11-14 18:53 ` Philippe Elie
2007-11-14 19:15 ` Andi Kleen
2007-11-15 0:07 ` Stephane Eranian
2007-11-13 18:47 ` Philip Mucci
2007-11-13 18:59 ` Greg KH
2007-11-13 20:07 ` Andrew Morton
2007-11-13 20:14 ` Greg KH
2007-11-13 20:36 ` Andi Kleen
2007-11-14 0:28 ` Philip Mucci
2007-11-14 1:52 ` Andi Kleen
2007-11-16 9:18 ` Philip Mucci
2007-11-16 15:15 ` Andi Kleen
2007-11-16 16:00 ` Stephane Eranian
2007-11-16 16:28 ` Andi Kleen
2007-11-16 17:13 ` William Cohen
2007-11-16 21:56 ` Stephane Eranian
2007-11-16 17:36 ` Stephane Eranian
2007-11-16 17:51 ` dean gaudet
2007-11-17 0:29 ` David Miller
2007-11-17 1:07 ` Greg KH
2007-11-16 20:16 ` Philip Mucci
2007-11-17 0:15 ` David Miller
[not found] ` <1d7226b10711161713j675341b7wdb4f050c59a8be0a@mail.gmail.com>
2007-11-17 1:25 ` Greg KH
[not found] ` <1d7226b10711161748n39b7f195q796d85282ef66134@mail.gmail.com>
2007-11-17 2:13 ` Greg KH
2007-11-14 7:24 ` [perfmon] Re: [perfmon2] " Paul Mackerras
2007-11-14 7:40 ` Andrew Morton
2007-11-14 10:38 ` Christoph Hellwig
2007-11-14 10:43 ` Paul Mackerras
2007-11-14 11:00 ` Christoph Hellwig
2007-11-14 11:12 ` David Miller
2007-11-14 11:14 ` David Miller
2007-11-14 11:44 ` Paul Mackerras
2007-11-13 23:49 ` Nick Piggin
2007-11-14 11:58 ` David Miller
2007-11-14 0:25 ` Nick Piggin
2007-11-14 21:30 ` Paul Mackerras
2007-11-14 10:17 ` Nick Piggin
2007-11-14 22:56 ` Chuck Ebbert
2007-11-14 11:03 ` Nick Piggin
2007-11-14 11:52 ` David Miller
2007-11-14 12:03 ` Paul Mackerras
2007-11-14 12:07 ` David Miller
2007-11-14 0:28 ` Nick Piggin
2007-11-14 21:50 ` Paul Mackerras
2007-11-14 23:03 ` David Miller
2007-11-14 23:12 ` Paul Mackerras
2007-11-14 23:21 ` David Miller
2007-11-15 1:11 ` Paul Mackerras
2007-11-15 1:27 ` David Miller
2007-11-15 2:34 ` Paul Mackerras
2007-11-15 7:48 ` Herbert Xu
2007-11-15 8:19 ` Andi Kleen
2007-11-19 13:08 ` David Miller
2007-11-19 20:53 ` Stephane Eranian
2007-11-20 0:55 ` David Miller
2007-11-19 21:43 ` Paul Mackerras
2007-11-19 22:48 ` Stephane Eranian
2007-11-20 0:53 ` David Miller
2007-12-13 16:00 ` Stephane Eranian
2007-12-14 19:12 ` Frank Ch. Eigler
2007-12-14 21:07 ` Stephane Eranian
2007-12-15 15:54 ` Frank Ch. Eigler
2007-11-15 8:29 ` [perfmon] " Stephane Eranian
2007-11-14 13:51 ` Stephane Eranian
2007-11-14 11:39 ` Paul Mackerras [this message]
2007-11-14 11:52 ` David Miller
2007-11-14 13:47 ` Stephane Eranian
2007-11-14 12:38 ` Andi Kleen
2007-11-14 14:13 ` Stephane Eranian
2007-11-14 14:26 ` Andi Kleen
2007-11-15 0:23 ` Paul Mackerras
2007-11-14 19:48 ` David Miller
2007-11-15 4:20 ` dean gaudet
2007-11-15 4:47 ` Paul Mackerras
2007-11-15 5:14 ` dean gaudet
2007-11-15 8:53 ` Stephane Eranian
2007-11-15 17:01 ` [perfmon2] [perfmon] " Dan Terpstra
2007-11-13 21:33 ` [perfmon] Re: [perfmon2] " Stephane Eranian
2007-11-13 21:45 ` Greg KH
2007-11-13 22:27 ` Christoph Hellwig
2007-11-13 20:42 ` Andi Kleen
2007-11-13 18:32 ` Stephane Eranian
2007-11-13 22:29 ` Christoph Hellwig
2007-11-16 18:25 ` PMC core internal API design Mathieu Desnoyers
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