From: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
To: linux-hotplug@vger.kernel.org
Subject: Re: [PATCH] util: Optimize path_encode
Date: Tue, 21 Oct 2008 21:41:02 +0000 [thread overview]
Message-ID: <48FE4C6E.2050607@tuffmail.co.uk> (raw)
In-Reply-To: <48FDAB29.9090401@tuffmail.co.uk>
Kay Sievers wrote:
> On Tue, Oct 21, 2008 at 12:12, Alan Jenkins <alan-jenkins@tuffmail.co.uk> wrote:
>
>> strncpy() shows up in profiling.
>> Since we already know the length, use memcpy() instead.
>>
>> Measured 2% _user_ cpu time reduction on EeePC coldplug
>>
>
> Applied.
>
> Thanks,
> Kay
>
Ah... just realised it wasn't the normal C string length inefficiency.
The problem was strncpy() doesn't stop after writing the terminating
NUL; by definition it goes on to zero the entire buffer.
I spy another use of strncpy in udev_device_add_property_from_string(),
which is responsible for another ~1% user cpu time...
BTW I'm still polishing threaded udevd in my spare time. It has 4
TODOs; I will post it soon anyway, but I need to write a few explanatory
words first. I have coarse-grained patch descriptions, but there are a
couple of obvious questions I would like to pre-answer :).
prev parent reply other threads:[~2008-10-21 21:41 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-21 10:12 [PATCH] util: Optimize path_encode Alan Jenkins
2008-10-21 11:12 ` Kay Sievers
2008-10-21 21:41 ` Alan Jenkins [this message]
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=48FE4C6E.2050607@tuffmail.co.uk \
--to=alan-jenkins@tuffmail.co.uk \
--cc=linux-hotplug@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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).