Hi, I ran some really trivial raw disk performance tests on 2.4.0 using the raw disk support in it. I seem to be getting some really strange performance results. My program opens up a raw device, then does a sequence of sequential/random reads/writes on the raw device using pread/pwrite. I put timing around both the sequence and the individual requests. I noticed that in some of the runs the elapsed time for the whole sequence of I/O requests is significantly longer than the sum of the individual I/O request response times (like 100 times longer say), yet my program does nothing in between the requests but a gettimeofday call to record the request starting time. The system has nothing else running when the tests were run, so the process should not be contenting with other things. This seems to me that somehow the raw device I/O process is either stuck or the linux scheduler is skewing things up somewhere. I tried to nice the process to higher priority values, it didn't seem to help. Any ideas? Thanks, Ying _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
