From: erik quanstrom <quanstro@quanstro.net>
To: 9fans@9fans.net
Subject: Re: [9fans] double wakeup disallowed
Date: Fri, 30 Oct 2009 10:11:45 -0400 [thread overview]
Message-ID: <7e75491a3122899dcc98ee196f3d9492@brasstown.quanstro.net> (raw)
In-Reply-To: <<dd6fe68a0910292245x70f83d7bl8957356abda38201@mail.gmail.com>>
On Fri Oct 30 01:47:06 EDT 2009, rsc@swtch.com wrote:
> > btw, isn't the lockstats.locks++ in taslock:/^lock
> > broken since >1 loads can happen simultaneously
> > leading to undercounting?
>
> sure but does it need to be 100% accurate?
probablly not. but it will be most inaccurate
and cause the most performance impact when
there's a lot of locking going on. i would think
that's exactly when it would be most interesting.
adding cores will make this worse, as does the
false sharing of the lockstats.
(i've seen some really wild results in my aoe
testing.)
so wouldn't xinc provide more consistent performance?
there would be at most 1 wait for the lockstats cacheline
per stat updated instead of 2.
- erik
next parent reply other threads:[~2009-10-30 14:11 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <<dd6fe68a0910292245x70f83d7bl8957356abda38201@mail.gmail.com>
2009-10-30 14:11 ` erik quanstrom [this message]
[not found] <<d73c6a7a4b7a22bffde73a5b0ec7a0b7@terzarima.net>
2009-10-28 13:24 ` erik quanstrom
2009-10-28 15:29 ` Russ Cox
2009-10-28 15:45 ` Charles Forsyth
2009-10-28 16:14 ` erik quanstrom
2009-10-30 5:45 ` Russ Cox
2009-10-27 23:38 erik quanstrom
2009-10-28 9:43 ` Charles Forsyth
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