Date: Thu, 18 Nov 1999 19:39:26 +0100 (CET) From: Remy Nonnenmacher <remy@synx.com> To: zab@zabbo.net Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: mbuf wait code (revisited) -- review? Message-ID: <199911181839.TAA39896@gw0.boostworks.com> In-Reply-To: <Pine.LNX.3.96.991118114107.30813W-100000@devserv.devel.redhat.com>
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On 18 Nov, Zach Brown wrote: > >> >(sysctl-ized) in FBSD (Some work have been done in Linux, since a >> >well-known comparative benchmark offense). Would be even more usefull >> >in SMP context. > > I don't think the wake-many problem was ever the cause of the poor numbers > that comparitve benchmark unearthed. This is only a problem if you have a > whole slew of children sitting around waiting for new connections, rather > than doing real work. this sure isn't the environment a heavily loaded > server is under :) If you're still curious, check out > > http://www.kegel.com/mindcraft_redux.html > > specifically > > http://kernelnotes.org/lnxlists/linux-kernel/lk_9906_04/msg01100.html > I agree that it is not the sole problem (as, for exemple, the discussions in the MC-redux shows that topics quickly went past the thundering herd) but it's a recurrent irritating (for mind) thing. Also, as the processes in a select/acccept loop will go user-mode, this means BGL contention in SMP, reducing the processing capacity to a single processor. I noticed that system activity tend to grow more quickly than user activity and these un-necessary wakeups are part of it. Am I wrong ? RN. IeM To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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