From owner-freebsd-hackers Thu Jan 31 16:40:54 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from web4.thecenturiongroup.com (112.mujb.nyrk.nycenycp.dsl.att.net [12.98.137.112]) by hub.freebsd.org (Postfix) with ESMTP id BE31F37B417 for ; Thu, 31 Jan 2002 16:40:25 -0800 (PST) Received: from ix1x1000 (ix1x1000.thecenturiongroup.com [192.32.248.52]) by web4.thecenturiongroup.com (Postfix) with SMTP id CF5077C001; Thu, 31 Jan 2002 19:40:24 -0500 (EST) Message-ID: <008201c1aab8$6f5636b0$34f820c0@ix1x1000> From: "Michael Meltzer" To: "Storms of Perfection" Cc: , , , References: <005b01c1aaaf$e38ecd70$34f820c0@ix1x1000> <3503.208.141.46.249.1012522251.squirrel@test.outloud.org> Subject: Re: Clock Granularity (kernel option HZ) Date: Thu, 31 Jan 2002 19:36:06 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG 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" To: Cc: ; ; ; 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" > > To: "Storms of Perfection" > > Cc: ; ; > > 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