Date: Mon, 12 Feb 2001 17:49:13 -0800 (PST) From: Matt Dillon <dillon@earth.backplane.com> To: Kent Stewart <kstewart@urx.com> Cc: Dag-Erling Smorgrav <des@ofug.org>, Greg Lehey <grog@lemis.com>, Danny Braniss <danny@cs.huji.ac.il>, freebsd-hackers@FreeBSD.ORG Subject: Re: soft updates performance Message-ID: <200102130149.f1D1nDr66705@earth.backplane.com> References: <E14RurO-0000Zl-00@cs.huji.ac.il> <xzp7l2wc6v6.fsf@flood.ping.uio.no> <20010213095300.D2178@wantadilla.lemis.com> <xzp3ddjpjlk.fsf@flood.ping.uio.no> <200102122343.f1CNhd053320@earth.backplane.com> <3A887EB3.6BDD7648@urx.com>
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:Thunderbird 900, with 256 MB of PC-133 memory, and using 3 - ATA-66
:HD's on different controllers. The elapsed time dropped from 58:16 to
:45:54 by using softupdates.
:
:Kent
That sounds about right for -pipe. The original email was
1 hour vs 40 minutes, a 20 minute difference which seemed a bit
high (what I would expect without -pipe). 46 minutes verses 58 minutes
is only a 12 minute 20 second difference, which is more inline with what
I would expect.
Most of the savings is occuring during the dependancy and
cleaning step(s). The system creates and deletes a huge
number of files in a huge number of directories and softupdates
really helps there.
Softupdates is not helping much during the actual compilation,
which is a cpu-bound step if you use -pipe (the creation of the
object files costs nothing because there is no other disk activity
going on).
The buildworld hits various choke points -- even with -j 128, if
there are only 30 files in a library you will generally only see
30 compiles going at once. The final library link stage chokes
it down to one process and this will become a pure bandwidth issue
for your disk subsystem for a second or so (for the larger libraries).
-Matt
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