<div dir="ltr">I had an old build of llc with FE instrumentation, the name section size is about 5MB. Using coverage is likely to cause the name section to be larger as there are more references to dead/unused function names.<div><br></div><div>What do you see when </div><div><br></div><div>readelf --string-dump=__llvm_prf_names llc</div><div><br></div><div>David</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Jun 27, 2017 at 2:23 PM, Xinliang David Li <span dir="ltr"><<a href="mailto:davidxl@google.com" target="_blank">davidxl@google.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote"><span class="">On Tue, Jun 27, 2017 at 2:09 PM, Friedman, Eli <span dir="ltr"><<a href="mailto:efriedma@codeaurora.org" target="_blank">efriedma@codeaurora.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div class="m_-8320681835050143414m_-4689985255915253797moz-cite-prefix">On 6/27/2017 1:47 PM, Xinliang David Li
wrote:<br>
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<div class="gmail_quote">On Mon, Jun 26, 2017 at 7:24 PM,
Friedman, Eli <span dir="ltr"><<a href="mailto:efriedma@codeaurora.org" target="_blank">efriedma@codeaurora.org</a>></span>
wrote:<br>
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<div class="m_-8320681835050143414m_-4689985255915253797m_-8178743545387745684moz-cite-prefix">On
6/19/2017 7:29 PM, Vedant Kumar wrote:<br>
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<div>We can reduce testing time by
*not* instrumented basic tools like
count, not, FileCheck etc. I filed:
<a href="http://llvm.org/PR33501" target="_blank">llvm.org/PR33501</a>.</div>
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<div>3. The generated profile
information takes up a lot of
space: llc generates a 90MB
profraw file.<br>
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<div>I don't have any ideas about how
to fix this. You can decrease the
space overhead for raw profiles by
altering <span>LLVM_PROFILE_</span><span>MERGE_P</span><span>O<wbr>OL_SIZE
from 4 to a lower value.</span></div>
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Disk space is cheap, but the I/O takes a
long time. I guess it's specifically bad
for LLVM's "make check", maybe not so bad
for other cases.<br>
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<div>You can speed up "make check" a bit by using
non-instrumented versions of count, not,
FileCheck, etc.</div>
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</span> I tried looking into this a bit more. It looks
like the profile data file generated by llc contains
approximately 5MB of counters (__llvm_prf_cnts), 10MB of
"data" (__llvm_prf_data), and 70MB of __llvm_prf_names.
__llvm_prf_data and __llvm_prf_names contain which can
be read from the original binary, as far as I can tell.
The 80MB of data wouldn't be a big deal if it were just
sitting on disk... but we also erase the whole file and
rewrite it from scratch after we merge profile counters.<br>
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<div>Can you check if name compression is turned on in your
build? </div>
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<div>David</div>
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I think it is. At least, I didn't intentionally turn it off, and
examining the file with objdump I don't see any uncompressed
strings. Not sure if there's any easy way to confirm that.</div></blockquote><div><br></div><div><br></div></span><div>Just a little surprised at the size of __llvm_prf_names section. The llc I built with IR PGO has a __llvm_prf_names section with size ~1.4MB. I expect FE instrumentation to produce larger name section size, but not so much bigger.</div><span class="HOEnZb"><font color="#888888"><div><br></div><div>David</div></font></span><span class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div text="#000000" bgcolor="#FFFFFF"><span><br>
<p>-Eli<br>
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<pre class="m_-8320681835050143414m_-4689985255915253797moz-signature" cols="72">--
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project</pre>
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