> Well, I based my argument from the 10 instances of reverse proxies > I'm running. It has 266,268,230 objects and 3.7 TB of space. CPU > usage is always around 0.2 according to ganglia. So unless you have > some other statistics to prove CPU is that important, I'm stick w/ my > argument that disk and RAM is way more important that CPU. > ok, reverse proxy does not so very much, so sure it depends on what you do with the machine > mike > > At 03:41 AM 7/6/2008, Michel wrote: > >> > The cpu doesn't do any IO, it's WAITING for the disk most of the >> > time. If you want fast squid performance, CPU speed/count is >> > irrelevant; get more disks and ram. When I mean more disk, I mean >> > more spindles. eg: 2x 100GB will is better than a 200GB disk. >> > >> >> >>well well, get prepared ... take your cpu out and then you'll see >>who is waiting >>forever :) >> >>even if IO wait is an issue it is or better WAS one on "old" giant >>lock systems >>where the cpu was waiting until getting the lock on a busy thread >>because there was >>only ONE CPU and even on multi-cpu-systems there was only one core a >>time bound to >>the kernel >> >>to get around this issue good old posix aio_*calls where used in >>order not to wait >>for a new lock what I believe is squid's aufs cache_dir model which >>is still very >>good and even better on modern smp machines and even with squid's >>not-smp-optimized >>code - you really can drain disks to their physical limits - but >>that is not all >> >>SMP (modern) works around the global giant lock, the kernel is not >>anymore limited >>to get one core a time >> >>SMP sistems are going to work with spin locks (Linux) and sleep >>locks (freebsd) >>where the linux way is focusing thread synchronizing which is going to be >>outperformanced by the sleep lock mechanism. Spin locks certainly >>still waste cpu >>while spinning what sleeplocks do not, cpu is free to do other work. >>This was kind >>of benefit for Linux last couple of years when freebsd was in deep >>developing of >>it's new threading model which is now on top I think, especially in >>shared memory >>environments. >> >>basicly is it not important if you use one or ten disks, this you >>should consider >>later as fine tuning but the threading model works the same, for one >>or two disks, >>or for 2 our 32Gigs of memory - so you certainly do NOT get araound >>your IO-Wait >>with more memory or more disk when the cpu(s) can not handle it >>"waiting for locks" >>as you say ... >> >>So IMO your statement is not so very true anymore, with a modern >>SMP-OS on modern >>smp hardware of course. >> >>michel >> >> >> >> >>**************************************************** >>Tecnologia Internet Matik http://info.matik.com.br >>Sistemas Wireless para o Provedor Banda Larga >>Hospedagem e Email personalizado - e claro, no Brasil. >>**************************************************** > > > > > > > > > A mensagem foi scaneada pelo sistema de e-mail e pode ser considerada segura. > Service fornecido pelo Datacenter Matik https://datacenter.matik.com.br > michel **************************************************** Tecnologia Internet Matik http://info.matik.com.br Sistemas Wireless para o Provedor Banda Larga Hospedagem e Email personalizado - e claro, no Brasil. ****************************************************
