Date: Tue, 22 Feb 2005 11:38:58 -0800 From: "Kevin Oberman" <oberman@es.net> To: Robert Watson <rwatson@FreeBSD.org> Cc: freebsd-stable@freebsd.org Subject: Re: HZ in RELENG_5? tcp_subr.c related Message-ID: <20050222193858.1C18C5D07@ptavv.es.net> In-Reply-To: Your message of "Tue, 22 Feb 2005 08:41:58 GMT." <Pine.NEB.3.96L.1050222084102.45557B-100000@fledge.watson.org>
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> Date: Tue, 22 Feb 2005 08:41:58 +0000 (GMT) > From: Robert Watson <rwatson@FreeBSD.org> > Sender: owner-freebsd-stable@freebsd.org > > > On Tue, 22 Feb 2005, Emanuel Strobl wrote: > > > I read this commit message to RELENG_5: > > http://www.freebsd.org/cgi/getmsg.cgi?fetch=436074+438355+/usr/local/www/db/text/2005/cvs-all/20050206.cvs-all > > and commented out the HZ=1000 line in my kernel config so I use the > > default. But I see only 100 interrupts/sec on clk (with systat) so is > > it true that the default HZ has changed from 100 to 1000 in RELENG_5? > > In RELENG_5, the default HZ for amd64 is 1000, but for all other platforms > it is 100. So amd64 users will see a ten-fold decrease in tcp_isn_tick() > running, but i386 (and other) users will see no change. Now that 5 is STABLE, I guess we are stuck with it, but in an era of "slow" 2GHz systems, it seems like a questionable choice. I know that there are a lot of folks running old hardware (like my trusty old K6), but they are a minority and changing HZ is not a big deal. Why make the majority live with 100 on fast systems or know enough to manually change it? Has there been discussion of changing this for V6 or is there a reason I missed for keeping HZ at 100 in the iX86 platforms. -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: oberman@es.net Phone: +1 510 486-8634
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