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To: Warner Losh <imp@bsdimp.com>
cc: Mark Johnston <markj@freebsd.org>, Andriy Gapon <avg@freebsd.org>,
 src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org,
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Subject: Re: svn commit: r326731 - head/sys/ufs/ffs
In-reply-to: <CANCZdfrQPSey1h+X_09GNJaeZqsZh6FmDXe6avO66qKEfAL=Pg@mail.gmail.com>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
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Date: Sun, 10 Dec 2017 00:17:03 +0000
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--------
In message <CANCZdfrQPSey1h+X_09GNJaeZqsZh6FmDXe6avO66qKEfAL=3DPg@mail.gma=
il.com>, Warner Losh writes:

>That would be strange given that BIO_ORDERED is @gibbs baby ?
>
>Nah... I wrote the iosched code... and I find the concept somewhat flawed
>since it is at the disk level, not the partition level, so it winds up
>interfering with mixed traffic. And it really only makes sense for writes=
,
>but it affects reads. And it is a poor fit to Ata semantics, and not a lo=
t
>better for scsi. And for nvme it creates a bottleneck in hardware careful=
ly
>designed to be free of bottlenecks...

Don't take my comment as an endorsement of BIO_ORDERED...

I think ordering is strictly a consumer responsibility for exactly
(and then some) of the reasons you mention.

"End to end principle in systems design" and all that...

-- =

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    =

Never attribute to malice what can adequately be explained by incompetence=
.