Date: Thu, 31 Jan 2002 19:36:06 -0500 From: "Michael Meltzer" <mjm@michaelmeltzer.com> To: "Storms of Perfection" <gary@outloud.org> Cc: <silby@silby.com>, <thierry@herbelot.com>, <replicator@ngs.ru>, <hackers@FreeBSD.ORG> Subject: Re: Clock Granularity (kernel option HZ) Message-ID: <008201c1aab8$6f5636b0$34f820c0@ix1x1000> References: <005b01c1aaaf$e38ecd70$34f820c0@ix1x1000> <3503.208.141.46.249.1012522251.squirrel@test.outloud.org>
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well I changed HZ=1000, recompiled and rebooted, ftp get and put, some nfs write big files and a app that pushes alot of small file reads, writes and rcp.lockd. No differance in the timings. Thier is a chance that the test client ran out of CPU but nothing that I spotted. MJM ----- Original Message ----- From: "Storms of Perfection" <gary@outloud.org> To: <mjm@michaelmeltzer.com> Cc: <silby@silby.com>; <thierry@herbelot.com>; <replicator@ngs.ru>; <hackers@FreeBSD.ORG> Sent: Thursday, January 31, 2002 7:10 PM Subject: Re: Clock Granularity (kernel option HZ) > Ok. Since I have a limited hardware/software set at my finger tips. I can > generate an attack on my machine (such as a synflood or something) to see > what type of reponses I can get by setting it up and down. I think this may > apply to this feature, to help the machine withstand attacks (and possibly > have performance related gains/decreases) > > I can't really play with gig-e or NFS at this second, so I ask you to play > around with the setting and keep track of what does what, and send a email > to me with what settings work best in foo enviornment :) > > > > Not knowing but wondering: > > With Gigabit Ethernet and NFS in the mix, anything that gets latency > > out is a very good thing :-) and would improve performance. > > > > MJM > > > > > > ----- Original Message ----- > > From: "Mike Silbersack" <silby@silby.com> > > To: "Storms of Perfection" <gary@outloud.org> > > Cc: <thierry@herbelot.com>; <replicator@ngs.ru>; <hackers@FreeBSD.ORG> > > Sent: Thursday, January 31, 2002 12:33 PM > > Subject: Re: Clock Granularity (kernel option HZ) > > > > > >> > >> On Thu, 31 Jan 2002, Storms of Perfection wrote: > >> > >> > I'm going to benchmark different network senarious with different > > options > >> > to see what I can get, and what works best. If someone wants to help > >> > me out, I could maybe write up a article about it? > >> > >> I don't think you'll end up seeing the performance improvements you're > >> looking for. The case where HZ=1000 is really useful is when using > >> dummynet; the more accurate scheduling is necessary for it to handle > >> high data rate pipes properly. > >> > >> The TCP stack, on the other hand, is perfectly happy with 10ms > >> resolution. Retransmission timeouts are only actually used when loss > >> occurs on the network, and 10ms is more than accurate enough for > >> retransmission. (I believe that retransmit timeouts are rounded up to > >> 1 second, but don't quote me on that.) The other timed events > >> (keepalive timeouts, delayed ack timeouts, etc) are also in good shape > >> with 10ms accuracy. > >> > >> So, it's highly unlikely that you'll be able to observe a perceptable > >> difference in network performance except in really convoluted cases. > >> > >> Mike "Silby" Silbersack > >> > >> > >> To Unsubscribe: send mail to majordomo@FreeBSD.org > >> with "unsubscribe freebsd-hackers" in the body of the message > > > Gary Stanley > Network Security Engineer > PRECISIONet/Webjockey, Inc. > (877) 595-8570 > > Tickle us, do we not laugh? Prick us, do we not bleed? Wrong us, shall we > not revenge?" (Merchant of Venice II i 56-63, paraphrase) > > > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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