From: abush wang <abushwangs@gmail.com>
To: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
Cc: abushwang via Libc-alpha <libc-alpha@sourceware.org>,
"H.J. Lu" <hjl.tools@gmail.com>,
Florian Weimer <fweimer@redhat.com>
Subject: Re: [PATCH] stdlib: reorganize stdlib Makefile routines by functionality
Date: Wed, 3 Apr 2024 09:57:44 +0800 [thread overview]
Message-ID: <CAMLoAPbqM3vXupzK25-KVThbhWG7pJ3Nun=2tovHsTR7GkacQQ@mail.gmail.com> (raw)
In-Reply-To: <2b5dde8f-2d72-4c76-bb93-347eade87a8f@linaro.org>
[-- Attachment #1: Type: text/plain, Size: 1408 bytes --]
I have try to add iteration like this
const int num_iterations = 100;
and I get:
Average time for lrand48: 37 cycles
there is a huge gap about the order of magnitude of cycles.
It seems like the first call for lrand48 do more thing than subsequent calls
On Tue, Apr 2, 2024 at 10:16 PM Adhemerval Zanella Netto <
adhemerval.zanella@linaro.org> wrote:
>
>
> On 01/04/24 08:47, abush wang wrote:
> > This is test:
> > ```
> > uint64_t getnsecs() {
> > uint32_t lo, hi;
> > __asm__ __volatile__ (
> > "rdtsc" : "=a"(lo), "=d"(hi)
> > );
> > return ((uint64_t)hi << 32) | lo;
> > }
> >
> > int main() {
> > const int num_iterations = 1;
>
> This low number of iteration makes the benchmark pretty much useless
> on modern hardware with frequency scaling. By raising to something
> like 1000000000 I see no variation on my workstation (Ryzen 5900).
>
> > uint64_t start, end, total_time = 0;
> >
> > start = getnsecs();
> > for (int i = 0; i < num_iterations; i++) {
> > (void) lrand48();
> > }
> > end = getnsecs();
> > total_time += (end - start);
> >
> > printf("Average time for lrand48: %lu cycles\n", total_time /
> num_iterations);
> > return 0;
> > }
> > ```
> > before:
> > Average time for lrand48: 21418 cycles
> >
> > after:
> > Average time for lrand48: 9892 cycles
>
[-- Attachment #2: Type: text/html, Size: 2148 bytes --]
next prev parent reply other threads:[~2024-04-03 1:58 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-01 11:47 [PATCH] stdlib: reorganize stdlib Makefile routines by functionality abush wang
2024-04-01 13:12 ` Florian Weimer
2024-04-01 13:17 ` H.J. Lu
2024-04-01 13:46 ` Adhemerval Zanella Netto
2024-04-02 3:54 ` abush wang
2024-04-08 2:48 ` abush wang
2024-04-02 2:17 ` abush wang
2024-04-02 2:28 ` abush wang
2024-04-02 3:13 ` H.J. Lu
2024-04-02 6:18 ` abush wang
2024-04-02 14:15 ` Adhemerval Zanella Netto
2024-04-03 1:57 ` abush wang [this message]
-- strict thread matches above, loose matches on Subject: below --
2024-04-01 11:44 abushwang
2024-04-01 12:03 ` Xi Ruoyao
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
List information: https://www.gnu.org/software/libc/involved.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAMLoAPbqM3vXupzK25-KVThbhWG7pJ3Nun=2tovHsTR7GkacQQ@mail.gmail.com' \
--to=abushwangs@gmail.com \
--cc=adhemerval.zanella@linaro.org \
--cc=fweimer@redhat.com \
--cc=hjl.tools@gmail.com \
--cc=libc-alpha@sourceware.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 read-only IMAP folder(s) and NNTP newsgroup(s).