From: Jeff Garzik <jeff@garzik.org>
To: Mark Lord <liml@rtr.ca>
Cc: "linux-ide@vger.kernel.org" <linux-ide@vger.kernel.org>,
Tejun Heo <htejun@gmail.com>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
Jens Axboe <axboe@suse.de>, Hannes Reinecke <hare@suse.de>
Subject: Re: jgarzik and max-sectors: out of memory
Date: Sat, 27 May 2006 16:02:06 -0400 [thread overview]
Message-ID: <4478B03E.9060202@garzik.org> (raw)
In-Reply-To: <4478AD4B.5090404@rtr.ca>
Mark Lord wrote:
> Jeff Garzik wrote:
> ..
>> Further -- someone with a long ATA memory correct me -- I think that
>> we can increase ATA_MAX_PRD beyond 256. Most DMA engines should just
>> keep chugging along, provided that we continue to respect the 64k IDE
>> DMA boundaries.
>
> MAX_PRD used to be equal to MAX_SECTORS, as that's the worst case scenario.
Not for lba48, which has a larger max-sectors but is still clamped to
the same 256 PRD entries...
> The only real gotcha I remember from the original IDE driver,
> was that some (very few) controllers were buggy with handing
> of a sector_count of zero (256), so setting the limit to a slightly
> lower value prevented that from ever being a problem.
Yeah, a couple of Alan's PATA drivers are fixed at 255.
> That was in the days before the block layer could limit the segment count.
Ahhhhh, useful to know.
Jeff
next prev parent reply other threads:[~2006-05-27 20:02 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-27 19:37 jgarzik and max-sectors: out of memory Jeff Garzik
2006-05-27 19:49 ` Mark Lord
2006-05-27 20:02 ` Jeff Garzik [this message]
2006-05-27 20:43 ` Jens Axboe
2006-05-30 4:58 ` Jeff Garzik
2006-05-30 8:36 ` Jens Axboe
2006-05-30 9:02 ` Jeff Garzik
2006-05-30 9:10 ` Jens Axboe
2006-05-30 9:15 ` Jeff Garzik
2006-05-30 9:25 ` Jens Axboe
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=4478B03E.9060202@garzik.org \
--to=jeff@garzik.org \
--cc=alan@lxorguk.ukuu.org.uk \
--cc=axboe@suse.de \
--cc=hare@suse.de \
--cc=htejun@gmail.com \
--cc=liml@rtr.ca \
--cc=linux-ide@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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.