Re: Cacheoff results published.

"Chemolli Francesco (USI)" wrote:
>
> [cut]
>
> > Our box was a Thunderbird 800, with 3 7200 RPM
> > disks, and 512MB of RAM. We couldn't handle more than 30 reqs/sec on
> > hardware that size. We've got our work cut out for us, eh?
>
> I am quite puzzled though, those results strike me at being quite low.

Ever tried a polymix-3 load? It's a very tough workload, especially for
Squid. (I assume because it's the cache Alex and Duane know best it
seems to hit Squid the hardest...we lost about 15-20% from Polymix-2 to
Polymix-3, whereas the best estimate of several ICS folks of their
lossage was only about 10%.) A Polymix-2 load on this box will run at
140...possibly more.

> I am running my production server on a Linux double PIII-500 w/ 5x9Gb SCSI
> reiserfs-formatted diskd-managed disks, 384 Mb of RAM, and at 50% (of only
> one)
> CPU load I can handle easily 85 reqs/sec, including NTLM authentication and
> authorization-checking against a 1700-users ACL (and the code
> to handle that sucks, I'm about to rewrite it as per Henrik's suggestion
> unless somebody beats me to it).
>
> This is a real-world situation, which might be different from others'
> since we have a pretty good upstream bandwidth and thus our FD-sets are
> usually pretty small (never seen more than 500 busy FDs).
> Also, a noticeable percentage of those hits are 407/auth-denied's needed
> to authenticate the clients (that are lighter than a 200/OK to manage)
>
> This said, I would expect to handle about 150 reqs/sec before I hit
> the limit and have to start thinking of ways to get to use the second CPU.

You'd probably be expecting too much. While the extra disks does make a
difference, you'll max out at well before 150 under polymix-3 load--and
you'll see severe hit lossage long before that (we're talking 35-40% hit
ratio when under moderate loads, I've done benchmarks with DiskD). In
fact, it sounds like you've got a box specced almost precisely like
Duane's cacheoff box that did 130. You'll probably gain about 15-20%
over that by using ReiserFS, but ReiserFS is somewhat harder on CPU...so
your CPU tends to become a limiting factor at some number of drives (3
for async, probably 4 for diskd).

Besides...You've also got a lot more hardware than our tested box. 5
SCSI drives is a far cry from three UDMA drives.

Squid is a lot of great things, but don't accuse it of being fast. ;-)

Also worth noting is that the simulated environment includes delays that
cause file descriptors to run at well over 1000...I think our box was
topping 2000 in the peak phases.
                                  --
                     Joe Cooper <joe@swelltech.com>
                 Affordable Web Caching Proxy Appliances
                        http://www.swelltech.com
Received on Thu Oct 12 2000 - 05:32:15 MDT