From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: James Bottomley <James.Bottomley@SteelEye.com>
Cc: Matthew Wilcox <matthew@wil.cx>, Jeremy Higdon <jeremy@sgi.com>,
Grant Grundler <grundler@parisc-linux.org>,
Jesse Barnes <jbarnes@engr.sgi.com>,
Matthew Wilcox <willy@debian.org>,
Andrew Vasquez <andrew.vasquez@qlogic.com>,
pj@sgi.com, SCSI Mailing List <linux-scsi@vger.kernel.org>,
mdr@cthulhu.engr.sgi.com, jeremy@cthulhu.engr.sgi.com,
djh@cthulhu.engr.sgi.com, Andrew Morton <akpm@osdl.org>,
Richard Henderson <rth@twiddle.net>,
Paul Mackerras <paulus@samba.org>
Subject: Re: I/O write ordering
Date: Thu, 23 Sep 2004 00:51:49 +1000 [thread overview]
Message-ID: <1095864709.6297.5.camel@gaston> (raw)
In-Reply-To: <1095864485.2143.1.camel@mulgrave>
> I favour 1. iomb; I think, since I/O barriers can be either heavyweight
> or non-existent depending on the architecture, iomb() should imply mb()
> but not vice versa.
Read & write barriers are different for IO. Actually, as I stated earlier,
the real issue isn't much with IO barriers proper (which are mostly dealt
with within the implementation of the IO accessors), but in IO vs. memory
accesses, at least on PPC. Cacheable and non-cacheable accesses go through
completely different path on the CPU and can be completely re-ordered one
to each other unless more heavy barriers are used. That has been a pain
for ages for us since Linux doesn't provide an abstraction to order those,
it would be nice to get that in place now ;)
Ben.
next prev parent reply other threads:[~2004-09-22 14:55 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <B179AE41C1147041AA1121F44614F0B060EF48@AVEXCH02.qlogic.org>
[not found] ` <20040916121235.5e4f9c32.pj@sgi.com>
[not found] ` <1095362263.16326.12.camel@praka>
2004-09-16 19:56 ` SCSI QLA not working on latest *-mm SN2 Paul Jackson
2004-09-16 20:05 ` Jesse Barnes
2004-09-16 20:56 ` Andrew Vasquez
2004-09-16 21:09 ` Jesse Barnes
2004-09-16 21:40 ` Andrew Vasquez
2004-09-16 22:25 ` Andrew Morton
2004-09-16 22:29 ` Jesse Barnes
2004-09-17 17:21 ` Jesse Barnes
2004-09-18 6:10 ` Grant Grundler
2004-09-18 17:57 ` Documentation/io_ordering.txt is wrong Matthew Wilcox
2004-09-20 23:39 ` Jesse Barnes
2004-09-21 0:38 ` Jesse Barnes
2004-09-20 22:40 ` SCSI QLA not working on latest *-mm SN2 Jesse Barnes
2004-09-20 23:27 ` Grant Grundler
2004-09-21 0:09 ` Jesse Barnes
2004-09-21 5:46 ` Grant Grundler
2004-09-21 6:45 ` Jeremy Higdon
2004-09-21 13:29 ` Jesse Barnes
2004-09-21 13:25 ` Jesse Barnes
2004-09-21 15:13 ` Jesse Barnes
2004-09-21 15:41 ` James Bottomley
2004-09-21 15:58 ` Jesse Barnes
2004-09-21 16:01 ` Matthew Wilcox
2004-09-21 16:05 ` Jesse Barnes
2004-09-21 16:11 ` James Bottomley
2004-09-21 16:18 ` Jesse Barnes
2004-09-21 16:24 ` James Bottomley
2004-09-21 17:03 ` Jesse Barnes
2004-09-21 17:15 ` Matthew Wilcox
2004-09-21 17:24 ` Jesse Barnes
2004-09-21 17:20 ` James Bottomley
2004-09-21 17:46 ` Jesse Barnes
2004-09-21 17:56 ` James Bottomley
2004-09-21 18:09 ` Jesse Barnes
2004-09-21 19:06 ` Grant Grundler
2004-09-21 19:40 ` Jesse Barnes
2004-09-21 22:44 ` Grant Grundler
2004-09-21 21:03 ` Jeremy Higdon
2004-09-21 21:11 ` Matthew Wilcox
2004-09-21 21:43 ` Jeremy Higdon
2004-09-21 22:33 ` Jesse Barnes
2004-09-22 0:02 ` Matthew Wilcox
2004-09-22 1:16 ` Jeremy Higdon
2004-09-22 1:44 ` Grant Grundler
2004-09-22 2:58 ` Jeremy Higdon
2004-09-22 14:32 ` I/O write ordering Matthew Wilcox
2004-09-22 14:40 ` Benjamin Herrenschmidt
2004-09-22 14:50 ` Jesse Barnes
2004-09-22 14:47 ` James Bottomley
2004-09-22 14:51 ` Benjamin Herrenschmidt [this message]
2004-09-22 15:11 ` James Bottomley
2004-09-22 15:11 ` Benjamin Herrenschmidt
2004-09-22 15:22 ` James Bottomley
2004-09-22 15:28 ` Benjamin Herrenschmidt
2004-09-22 15:43 ` James Bottomley
2004-09-23 0:19 ` Benjamin Herrenschmidt
2004-09-23 1:58 ` Matthew Wilcox
2004-09-23 3:01 ` James Bottomley
2004-09-23 3:40 ` Benjamin Herrenschmidt
2004-09-23 4:26 ` Grant Grundler
2004-09-21 23:03 ` SCSI QLA not working on latest *-mm SN2 Guennadi Liakhovetski
2004-09-16 23:14 ` Jeremy Higdon
2004-09-16 20:11 ` Andrew Morton
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1095864709.6297.5.camel@gaston \
--to=benh@kernel.crashing.org \
--cc=James.Bottomley@SteelEye.com \
--cc=akpm@osdl.org \
--cc=andrew.vasquez@qlogic.com \
--cc=djh@cthulhu.engr.sgi.com \
--cc=grundler@parisc-linux.org \
--cc=jbarnes@engr.sgi.com \
--cc=jeremy@cthulhu.engr.sgi.com \
--cc=jeremy@sgi.com \
--cc=linux-scsi@vger.kernel.org \
--cc=matthew@wil.cx \
--cc=mdr@cthulhu.engr.sgi.com \
--cc=paulus@samba.org \
--cc=pj@sgi.com \
--cc=rth@twiddle.net \
--cc=willy@debian.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox