[cfe-dev] clang performance when building Linux

[Chandler Carruth]

On Sat, Apr 16, 2011 at 5:01 AM, Benjamin Kramer
<benny.kra at googlemail.com>wrote:

> >     3.65%     clang  clang                              [.]
> llvm::StringMapImpl::LookupBucketFor(llvm::StringRef)
>
> I'm a bit surprised that StringMap is the most expensive entry here, maybe
> microoptimizing
> the hash function (which is a byte-wise djb hash at the moment) can help a
> bit. If someone is
> really bored it would also be useful to test if other string hash functions
> like murmurhash or google's
> new city hash give better performance.
>

Interesting. I'm familiar with murmurhash and watched the development of
city hash and am quite familiar with it. I'll take a look at what it would
take to use cityhash here. Anything special done to produce these numbers?
Just a build of the kernel?

If you could paste how you collected the perf data that would be useful as
well... i've not used the 'perf' tool extensively before.
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