linux-kernel - Re: [PATCH] block: fix q->max_segment_size checking in blk_recalc_rq

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sun, 20 Jul 2008 09:52:25 -0500
From:	James Bottomley <James.Bottomley@...senPartnership.com>
To:	David Miller <davem@...emloft.net>
Cc:	mpatocka@...hat.com, fujita.tomonori@....ntt.co.jp,
	jens.axboe@...cle.com, linux-kernel@...r.kernel.org,
	linux-scsi@...r.kernel.org, linux-parisc@...r.kernel.org
Subject: Re: [PATCH] block: fix q->max_segment_size checking in
	blk_recalc_rq_segments about VMERGE

On Sat, 2008-07-19 at 21:07 -0700, David Miller wrote:
> From: James Bottomley <James.Bottomley@...senPartnership.com>
> Date: Sat, 19 Jul 2008 21:17:08 -0500
> 
> > Try this patch
> 
> I'd rather remove the vmerge code, it doesn't buy us
> anything, and for something so complex and so hard to
> keep working correctly it's existence is far from
> justified these days.

You can ... as soon as BIO_VMERGE_BOUNDARY is undefined or set to zero,
it gets compiled out of the block code. 

Since we're using it successfully in parisc, I don't want the block code
removed, but I don't see a reason to force other architectures to use
it.

However, it has two use cases.  One is the legacy one of making rather
dumb I/O cards perform better (which is the primary on on parisc), but
there is a current one making huge transfers go through SCSI using using
the sg_table code.  That latter is pretty vital to me since I have to
keep the code working, but I don't really have any SCSI cards that can
take advantage of it without virtual merging.  As a slight irony, IBM is
trying to persuade me that a ppc would be better than a parisc for big
endian I/O testing ... so I might just be seeing if I can make virtual
merging work on power too.

James

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/