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List Archive: gentoo-performance
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To: gentoo-performance@g.o
From: "Michael W Spitzer" <mwspitzer@...>
Subject: Re: performance testing
Date: Mon, 30 Apr 2007 07:30:26 -0500
I&#39;d agree with Miguel. In general, I can&#39;t tell the difference in most applications. I did some tests on OpenOffice a few years ago and found the 8 hour compile time wasn&#39;t worth it in terms of performance. Where Gentoo shines is in giving you the increased ability to shrink your installed size. I have nothing on this machine that I don&#39;t specifically want there and I work overly hard to keep my compile flags exactly right.
<br><br>That said, I&#39;d be interested in seeing your results. It would be nice to know that all of this work is beneficial for more than just keeping me happy.<br><br>Mike<br><br><div><span class="gmail_quote">On 4/30/07, 
<b class="gmail_sendername">Miguel Sousa Filipe</b> &lt;<a href="mailto:miguel.filipe@...">miguel.filipe@...</a>&gt; wrote:</span><blockquote class="gmail_quote" style="margin-top: 0; margin-right: 0; margin-bottom: 0; margin-left: 0; margin-left: 0.80ex; border-left-color: #cccccc; border-left-width: 1px; border-left-style: solid; padding-left: 1ex">
Hi there,<br><br>On 4/29/07, Peter A. H. Peterson &lt;<a href="mailto:pedro@...">pedro@...</a>&gt; wrote:<br>&gt; Hi Everyone,<br>&gt;<br>&gt; My name is Peter Peterson and I represent a group of a grad students
<br>&gt; at UCLA. We&#39;re in a computer systems performance analysis course and we<br>&gt; were hoping to do a general performance comparison of gentoo vs. a<br>&gt; popular binary i386-compatible distribution (probably ubuntu) in some
<br>&gt; &quot;real-world&quot; server tests to try and meaningfully calculate the<br>&gt; performance gains that local compilation provides. (For example,<br>&gt; apache2 requests processed per second on the same hardware.)
<br>&gt;<br>&gt; I&#39;ve subscribed to this list because we want the gentoo community to<br>&gt; be involved in helping us design the tests so that we can hopefully<br>&gt; all feel good about what and how we are testing the systems.
<br>&gt;<br>&gt; We have no particular outcome in mind; our group represents a wide<br>&gt; range of computer users, from Mac, Linux, and Windows enthusiasts, and<br>&gt; we have all used a wide variety of Linux distributions. We have simply
<br>&gt; noticed that much of the discussion of gentoo&#39;s performance advantage<br>&gt; is anecdotal and we&#39;re genuinely hoping to provide some meaningful<br>&gt; experimental data for discussion. Also, if anyone knows of any
<br>&gt; available benchmark data or papers on this subject, we&#39;d love to hear<br>&gt; about them. There was apparently a paper on slashdot a couple of years<br>&gt; ago, but the host it was on appears to now be squatted. For that
<br>&gt; matter, if this is a well understood or closed issue (for example, if<br>&gt; the statistics that people quote are actually from good experimental<br>&gt; data) please let us know.<br>&gt;<br>&gt; Is anyone here interested in discussing this project? We are
<br>&gt; specifically interested in discussing methodology, testing suits,<br>&gt; CFLAGS and other options. Our desire is not to &quot;trick out&quot; gentoo or<br>&gt; ubuntu, but rather quantify the performance benefit that gentoo has
<br>&gt; over binary distributions with &quot;normal&quot; compile flags (whatever normal<br>&gt; is).<br>&gt;<br><br>A good CFLAGS would be something not very agressive, something like:<br>-march=&lt;cpuType&gt; -O3 or -O2 and at most -fomit-frame-pointer.
<br>(Scientific workloads can speedup considerably with: -ffast-math)<br><br>Having experienced and done some benchmarks with gentoo and other<br>distros on servers and on scientific workstations.<br> What I found is that sometimes gentoo lacks critical performance
<br>patches in glibc that are applied to mainstream distros (redhat,<br>suse..etc) that provide boosts in memcpy, memset, etc..(I remmember a<br>discussion about that some years ago).<br> What I also found out is that the compiler flags only affect
<br>workloads that are very compute intensive. not something that depends<br>almost completely on FSB load or IO load.. like most server<br>workloads... -O3 doesn&#39;t do much to a working set full of<br>unpredictable branches (like server workloads usually are) and low IPC
<br>rate.<br><br>I really do believe performance boost from gentoo to be practically<br>negligible. The difference will only be apreciable in very few corner<br>cases. Most distros also optimize critical aplications such has:
<br>openssl, mplayer.. reducing the possible corner cases.<br><br>Anyways, doing a &quot;academic&quot; benchmark would be a good idea.<br><br>Something like:<br>micro-benchmarks:<br>- stream (mem bandwith benchmark)<br>- ??
<br><br>macro-benchmarks:<br>- apache2 + gzip + php(make it cpu intensive, not IO intensive)<br>- xmlmark ?<br>- kernelbench<br>- pybench ?<br>- openssl bench<br><br><br>about methodology:<br>- same system, same bios version, same disks.
<br>- All OSes must be installed in the same disk partitions.<br>- the will be trouble about the kernel config:<br>&nbsp;&nbsp;- for mainstream distros you should use the kernel that is provided.<br>&nbsp;&nbsp;- for gentoo, gentoo-sources configured by someone which is
<br>experienced, and informed about configuration impacts on performance<br>(ideally a kernel hacker?).<br><br>- should use the stable versions in gentoo portage?<br>- or should use the same application versions used on mainstream distro?
<br><br><br><br>--<br>Miguel Sousa Filipe<br>--<br><a href="mailto:gentoo-performance@g.o">gentoo-performance@g.o</a> mailing list<br><br></blockquote></div><br>
performance testing
-- Peter A. H. Peterson
Re: performance testing
-- Miguel Sousa Filipe
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