linux-kernel - loop block-mq conversion scalability issues

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: Windows password security audit tool. GUI, reports in PDF.

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

Date:	Thu, 23 Apr 2015 16:04:10 -0500
From:	"Justin M. Forbes" <jforbes@...hat.com>
To:	ming.lei@...onical.com
Cc:	linux-kernel <linux-kernel@...r.kernel.org>
Subject: loop block-mq conversion scalability issues

The block-mq conversion for loop in 4.0 kernels is showing us an
interesting scalability problem with live CDs (ro, squashfs).  It was
noticed when testing the Fedora beta that the more CPUs a liveCD image
was given, the slower it would boot. A 4 core qemu instance or bare
metal instance took more than twice as long to boot compared to a single
CPU instance.  After investigating, this came directly to the block-mq
conversion, reverting these 4 patches will return performance. More
details are available at
https://bugzilla.redhat.com/show_bug.cgi?id=1210857
I don't think that reverting the patches is the ideal solution so I am
looking for other options.  Since you know this code a bit better than I
do I thought I would run it by you while I am looking as well.

Thanks,
Justin

--
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/