From: Keith Owens <kaos@ocs.com.au>
To: Erik Slagter <erik@slagter.name>
Cc: linux-kernel@vger.kernel.org
Subject: Re: md mirror / ext3 / dual core performance strange phenomenon?
Date: Mon, 14 Aug 2006 23:22:02 +1000 [thread overview]
Message-ID: <10837.1155561722@ocs10w.ocs.com.au> (raw)
In-Reply-To: Your message of "Mon, 14 Aug 2006 15:12:14 +0200." <1155561134.7809.27.camel@skylla.slagter.name>
Erik Slagter (on Mon, 14 Aug 2006 15:12:14 +0200) wrote:
>Now, what puzzles me, is that compiling the kernel (2.6.17.7) using
>either "make -j1 ..." or "make -j2 ..." or "make -j3 ..." makes the
>building take about 6.5 minutes, which is really dissatisfying for this
>cpu/harddisks combination. Also, top shows that most of the time both
>core are between 10-40% idle.
>
>BUT... starting from -j4 (and upwards) the compile time suddenly goes to
>3.5 minutes!
Nothing to do with the disks, it is a design flaw in the kernel build
system. If you want a useful parallel make using -j<n>, set <n> to 3,
4 or 5 higher than the real number of parallel jobs that you want. The
exact value to add depends on which kernel tree you are building. See
http://marc.theaimsgroup.com/?l=linux-kernel&m=115553906404695&w=2
next prev parent reply other threads:[~2006-08-14 13:22 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-14 13:12 Erik Slagter
2006-08-14 13:22 ` Keith Owens [this message]
2006-08-14 13:26 ` Erik Slagter
2006-08-14 14:48 ` Alistair John Strachan
2006-08-14 14:01 ` Alan Cox
2006-08-14 13:49 ` Erik Slagter
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=10837.1155561722@ocs10w.ocs.com.au \
--to=kaos@ocs.com.au \
--cc=erik@slagter.name \
--cc=linux-kernel@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
all inboxes | Powered by JetHome®