From: "Paul E. McKenney" <paulmck@kernel.org>
To: Alan Huang <mmpgouride@gmail.com>
Cc: akiyks@gmail.com, perfbook@vger.kernel.org
Subject: Re: [PATCH] CodeSamples/defer: Make hazard partition consistent with hazptr_thread_exit
Date: Tue, 25 Apr 2023 11:36:26 -0700 [thread overview]
Message-ID: <c7d8bbb9-0cad-47b8-af71-3a6489bff0a6@paulmck-laptop> (raw)
In-Reply-To: <28115808-37F7-4003-BD8B-E15D12DC6B70@gmail.com>
On Tue, Apr 25, 2023 at 09:32:46PM +0800, Alan Huang wrote:
> > 2023年4月25日 00:02，Paul E. McKenney <paulmck@kernel.org> 写道：
> >
> > On Thu, Apr 20, 2023 at 07:40:30AM +0000, Alan Huang wrote:
> >> Signed-off-by: Alan Huang <mmpgouride@gmail.com>
> >> ---
> >> CodeSamples/defer/hazptrtorture.h | 2 +-
> >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/CodeSamples/defer/hazptrtorture.h b/CodeSamples/defer/hazptrtorture.h
> >> index 29761e3d..acdd532b 100644
> >> --- a/CodeSamples/defer/hazptrtorture.h
> >> +++ b/CodeSamples/defer/hazptrtorture.h
> >> @@ -99,7 +99,7 @@ void *hazptr_read_perf_test(void *arg)
> >> {
> >> int i;
> >> int me = (long)arg;
> >> - int base = me * K;
> >> + int base = smp_thread_id() * K;
> >
> > Suppose specify a number of threads greater than the number of CPUs.
> > For example, on my 12-hardware-thread laptop:
> >
> > ./route_hazptr --stresstest --nreaders 24
> >
> > In that case, don't we want "me" rather than "smp_thread_id()"?
Never mind, I was confused. Maybe I should have waited another
day after return before looking at this. :-/
$ ./hazptr 24 perf
sched_setaffinity: Invalid argument
Aborted (core dumped)
But that is a pre-existing problem. If I keep the number within the
number of hardware threads, it works fine:
$ ./hazptr 12 perf
n_reads: 576608000 n_updates: 314343 nreaders: 12 nupdaters: 1 duration: 1
ns/read: 20.8114 ns/update: 3181.24
I am not all that worried about this. Running multiple threads per
hardware thread in a performance test isn't all that useful, after all.
And there is a robust diagnostic. Perhaps not as helpful as one might
like, but definitely robust. ;-)
> As Akira said, route_hazptr.c includes routetorture.h and route_hazptr.c doesn't call hp_record().
> The fix won't have any effect on route_hazptr.
Agreed, again, my post-vacation confusion, apologies!!!
Thanx, Paul
prev parent reply other threads:[~2023-04-25 18:36 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-20 7:40 [PATCH] CodeSamples/defer: Make hazard partition consistent with hazptr_thread_exit Alan Huang
2023-04-24 16:02 ` Paul E. McKenney
2023-04-25 3:39 ` Akira Yokosawa
2023-04-25 13:32 ` Alan Huang
2023-04-25 18:36 ` Paul E. McKenney [this message]
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=c7d8bbb9-0cad-47b8-af71-3a6489bff0a6@paulmck-laptop \
--to=paulmck@kernel.org \
--cc=akiyks@gmail.com \
--cc=mmpgouride@gmail.com \
--cc=perfbook@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 read-only IMAP folder(s) and NNTP newsgroup(s).