GiM wrote: > To ClamAV users ML in message 'Re: [Clamav-users] XML and large file scan > performance' wrote: >> 7MB XML file in 0.3s ? >> >> let's do some math: >> 7*1024^2 * 10 /3 / 1024^2 >> 23.3 MB/s >> >> Do you have SCSI drive ? >> Cause, correct me if I'm wrong the fastest transfer rate on ATA is about >> 17MB/s and 40MB/s on SCSI device. > > I've checked, that UDMA6 should be able to do 133M/s and > SATA even 150M/s, but this depends on both hardware and system.
It has more to do with the type of test (sequential or random), then with the environment. Take a look at the difference, using a Western Digital WD1200JB (7200 RPM, 8MB cache, UDMA5) with Sandra: Benchmark Breakdown Buffered Read : 80 MB/s Sequential Read : 45 MB/s Random Read : 7 MB/s Buffered Write : 89 MB/s Sequential Write : 42 MB/s Random Write : 13 MB/s Average Access Time : 8 ms (estimated) The 133MB/s # you mentioned is the bus speed, or what you can do ideally if you only make small transactions which stay in cache. In practice, you top out at 90% of the IDE bus speed. And a real world virus scanner is going to always be dealing with new incoming data, most probably with multiple scanner processes or threads going on (so I/O is heavily multithreaded), all of which means numbers around 10-15 MB/s for IDE drives are realistic. :-) > I'm quite curious what was the enviroment you were making your tests on. Something like this on Unix: dd if=/dev/disk of=/dev/null bs=8k ...is a reasonable benchmark (at least for ballpark # purposes), so long as you read enough data to exceed any caching in RAM. [ Now, if you've got enough RAM, perhaps you can do your virus scanning entirely via a pipeline or socket, without ever hitting disk, which could explain a faster time you saw, but the Subject of the thread suggests we're dealing with a file on disk. Besides, the MTA shouldn't confirm receipt of a message until it's written to permanent storage. ] -- -Chuck _______________________________________________ http://lurker.clamav.net/list/clamav-users.html
