From: Bill Wendling <morbo@google.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: dwarves@vger.kernel.org, bpf <bpf@vger.kernel.org>,
Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Subject: Re: [PATCH] dwarf_loader: use a better hashing function
Date: Wed, 10 Feb 2021 17:24:06 -0800 [thread overview]
Message-ID: <CAGG=3QW0zuXUcpkcZqnaZS77EABEshhPtUCTr71dDDMuL1oMZQ@mail.gmail.com> (raw)
In-Reply-To: <CAEf4BzYrWe4N28JjM6na=sNvq5214zs5yHra_fCuE1KA24KQ0A@mail.gmail.com>
On Wed, Feb 10, 2021 at 4:00 PM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Wed, Feb 10, 2021 at 3:25 PM Bill Wendling <morbo@google.com> wrote:
> >
> > This hashing function[1] produces better hash table bucket
> > distributions. The original hashing function always produced zeros in
> > the three least significant bits.
> >
> > The new hashing funciton gives a modest performance boost.
> >
> > Original New
> > 0:11.41 0:11.38
> > 0:11.36 0:11.34
> > 0:11.35 0:11.26
> > -----------------------
> > Avg: 0:11.373 0:11.327
> >
> > for a performance improvement of 0.4%.
> >
> > [1] From Numerical Recipes, 3rd Ed. 7.1.4 Random Hashes and Random Bytes
> >
>
> Can you please also test with the one libbpf uses internally:
>
> return (val * 11400714819323198485llu) >> (64 - bits);
>
> ?
>
> Thanks!
>
It's giving me a running time of ~11.11s, which is even better. Would
you like me to submit a patch?
-bw
next prev parent reply other threads:[~2021-02-11 1:25 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-10 23:23 [PATCH] dwarf_loader: use a better hashing function Bill Wendling
2021-02-10 23:59 ` Andrii Nakryiko
2021-02-11 1:24 ` Bill Wendling [this message]
2021-02-11 1:31 ` Andrii Nakryiko
2021-02-11 13:01 ` Arnaldo Carvalho de Melo
2021-02-12 6:55 ` Bill Wendling
2021-02-12 12:35 ` Arnaldo Carvalho de Melo
2021-02-12 8:01 ` [PATCH v2] " Bill Wendling
2021-02-12 12:37 ` Arnaldo Carvalho de Melo
2021-02-12 12:39 ` Arnaldo Carvalho de Melo
2021-02-12 20:14 ` Bill Wendling
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAGG=3QW0zuXUcpkcZqnaZS77EABEshhPtUCTr71dDDMuL1oMZQ@mail.gmail.com' \
--to=morbo@google.com \
--cc=andrii.nakryiko@gmail.com \
--cc=arnaldo.melo@gmail.com \
--cc=bpf@vger.kernel.org \
--cc=dwarves@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).