From: Michael Tokarev <mjt@tls.msk.ru>
To: Will Drewry <wad@chromium.org>
Cc: Stephen Warren <swarren@wwwdotorg.org>, Tejun Heo <tj@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"cross-distro@lists.linaro.org" <cross-distro@lists.linaro.org>,
Jens Axboe <axboe@kernel.dk>, Kay Sievers <kay.sievers@vrfy.org>
Subject: Re: root=PARTUUID for MBR/NT disk signatures?
Date: Tue, 21 Aug 2012 10:38:39 +0400 [thread overview]
Message-ID: <50332CEF.7010204@msgid.tls.msk.ru> (raw)
In-Reply-To: <CABqD9hY-Z9uBcYyeCa=8f8eeXkGNjPKxbwpMPi3vs3776vF6iQ@mail.gmail.com>
On 21.08.2012 08:47, Will Drewry wrote:
[]
> Functionally, I suspect this will work fine, but I am concerned that
> it is a bad move from an efficiency perspective (not unfixable
> though). Right now, the user-supplied value is converted from
> string-uuid to packed-uuid. This is then memcmp'd across any and all
> partitions - be it 2 or 200 - across all attached storage. If we move
> to a pure string, then we end up needing to unpack every packed UUID
> at disk scan time (or search, depending on impl) rather than just the
> one user supplied value.
>
> Perhaps the cost is negligible on modern machines, but it seems like
> the wrong place to put the cost (per entry rather than per search
> value).
Amount of work needed to READ all the partition tables might be
quite a bit larger than strcmp'ing it all. I think.
/mjt
next prev parent reply other threads:[~2012-08-21 6:38 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-17 22:10 root=PARTUUID for MBR/NT disk signatures? Stephen Warren
2012-08-20 18:22 ` Tejun Heo
2012-08-20 18:30 ` Stephen Warren
2012-08-21 4:47 ` Will Drewry
2012-08-21 6:38 ` Michael Tokarev [this message]
2012-08-21 18:08 ` Stephen Warren
2012-08-21 18:47 ` Will Drewry
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