<html>
<head>
<base href="https://bugs.webkit.org/" />
</head>
<body>
<p>
<div>
<b><a class="bz_bug_link
bz_status_NEW "
title="NEW - IdentifierRepHash has a mismatch between hash() and equal()"
href="https://bugs.webkit.org/show_bug.cgi?id=150137#c5">Comment # 5</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW - IdentifierRepHash has a mismatch between hash() and equal()"
href="https://bugs.webkit.org/show_bug.cgi?id=150137">bug 150137</a>
from <span class="vcard"><a class="email" href="mailto:utatane.tea@gmail.com" title="Yusuke Suzuki <utatane.tea@gmail.com>"> <span class="fn">Yusuke Suzuki</span></a>
</span></b>
<pre>(In reply to <a href="show_bug.cgi?id=150137#c3">comment #3</a>)
<span class="quote">> Do you recommend measuring distribution directly, or do you think it's OK to
> just see how performance is affected overall?</span >
I was thinking about HashTable::dumpStats.
DUMP_HASHTABLE_STATS can dump the statistics including collisions.
<span class="quote">> We may encounter a trade-off between a fast to compute hash function that
> gives worse distribution and a slow to compute hash function that gives
> better distribution. I don't have a philosophical preference between the
> two, but I just suspect that unless the distribution is really bad, the
> faster-to-compute hash function will give better overall performance. Maybe
> the best thing to do is just to look at end-to-end performance. Probably,
> it doesn't matter at all. In that case, PtrHash is nicer because it's the
> less surprising choice.</span >
Agreed. If the change does not pose any performance regression & there are enough tests, I think it indirectly indicates the distribution of PtrHash is not so bad.</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are the assignee for the bug.</li>
</ul>
</body>
</html>