From: Pete Zaitcev <zaitcev@redhat.com>
To: Krzysztof Halasa <khc@pm.waw.pl>
Cc: linux-kernel@vger.kernel.org, Pete Zaitcev <zaitcev@redhat.com>
Subject: Re: [PATCH] RFC: kills consistent_dma_mask
Date: Mon, 18 Aug 2003 11:15:22 -0400 [thread overview]
Message-ID: <20030818111522.A12835@devserv.devel.redhat.com> (raw)
In-Reply-To: <m3oeynykuu.fsf@defiant.pm.waw.pl>; from khc@pm.waw.pl on Mon, Aug 18, 2003 at 12:34:17AM +0200
> From: Krzysztof Halasa <khc@pm.waw.pl>
> Date: 18 Aug 2003 00:34:17 +0200
> It's unneeded (it can be easily done in a driver, should a need arrive,
> without polluting the PCI subsystem) and is not supported by "DMA" API.
Are you talking about doing tripple calls, e.g.
pci_set_dma_mask(pdev, 0xFFFFFFFF);
foo = pci_alloc_consistent(pdev, size, &handle);
// Restore for upcoming streaming allocations
pci_set_dma_mask(pdev, 0xFFFFFFFFFFFFFFFF);
Possibly Jes considered that alternative and decided that it
did not allow for sufficient performance.
> It isn't even implemented on most platforms - only x86_64 and ia64 have
> support for it, while on the remaining archs using it according to the
> docs (with non-default value) could mean Oops or something like that.
Before you go for that, I'd rather see you implementing the
double/tripple calls in drivers, check for effects, THEN
go for removal of the mask. If you cannot do it, plea SGI people
to test it on SN-2 for you (or same for Intel Tiger box).
> This patch doesn't actually change any current kernel behaviour.
Sure it does. It blows all non-mmu ia64 out of the water.
The consistent mask looks a little distasteful to me, and I think
it should not buy us performance because consistent allocations
are not supposed to be fast. They are bad, but what you are doing
is worse: you are trying to ruin the day of legitimate users.
Please, be reasonable. Get SGI buy-in and come back.
-- Pete
next prev parent reply other threads:[~2003-08-18 15:15 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-08-17 22:34 [PATCH] RFC: kills consistent_dma_mask Krzysztof Halasa
2003-08-18 6:37 ` David S. Miller
2003-08-18 12:44 ` Krzysztof Halasa
2003-08-18 12:43 ` David S. Miller
2003-08-18 15:54 ` Krzysztof Halasa
2003-08-18 16:49 ` David S. Miller
2003-08-18 18:21 ` Krzysztof Halasa
2003-08-18 18:50 ` David S. Miller
2003-08-18 21:58 ` Krzysztof Halasa
2003-08-19 9:24 ` Jes Sorensen
2003-08-19 9:21 ` Jes Sorensen
2003-08-18 13:00 ` Jes Sorensen
2003-08-18 8:07 ` Christoph Hellwig
2003-08-18 15:15 ` Pete Zaitcev [this message]
2003-08-18 16:14 ` Krzysztof Halasa
2003-08-19 9:16 ` Jes Sorensen
2003-08-19 9:49 ` Krzysztof Halasa
2003-08-19 10:15 ` Jes Sorensen
2003-08-19 9:03 ` Jes Sorensen
2003-08-19 13:07 ` Alan Cox
2003-08-19 13:20 ` Jes Sorensen
2003-08-19 16:55 ` David S. Miller
2003-08-19 18:33 ` Alan Cox
2003-08-19 18:31 ` David S. Miller
2003-08-19 20:31 ` Krzysztof Halasa
2003-08-22 11:54 ` Krzysztof Halasa
2003-08-23 17:11 ` Jes Sorensen
2003-08-24 12:06 ` Krzysztof Halasa
2003-08-24 13:00 ` David S. Miller
2003-08-24 19:58 ` Krzysztof Halasa
2003-08-25 8:50 ` Jes Sorensen
2003-08-30 21:18 ` Krzysztof Halasa
2003-08-31 1:50 ` David S. Miller
2003-08-31 12:52 ` Alan Cox
2003-08-31 15:24 ` Krzysztof Halasa
2003-09-01 5:22 ` David S. Miller
2003-09-01 7:34 ` Krzysztof Halasa
2003-09-01 7:43 ` David S. Miller
2003-09-01 17:14 ` Krzysztof Halasa
2003-09-01 17:28 ` David S. Miller
2003-09-01 18:24 ` Krzysztof Halasa
2003-09-01 7:54 ` Alan Cox
2003-09-01 7:52 ` David S. Miller
2003-09-01 16:27 ` Krzysztof Halasa
2003-09-01 17:33 ` David S. Miller
2003-08-25 8:47 ` Jes Sorensen
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=20030818111522.A12835@devserv.devel.redhat.com \
--to=zaitcev@redhat.com \
--cc=khc@pm.waw.pl \
--cc=linux-kernel@vger.kernel.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;
as well as URLs for NNTP newsgroup(s).