On Tue, Nov 16, 2010 at 6:32 AM, John <[email protected]> wrote: >> You're also missing the design limitations of the actual drives. Assuming >> IDE/SATA, the disks do not support disconnected writes, which is a >> significant performance bottleneck when you are writing to the >> disk...SAS/SCSI drives have 128 concurrent writes (tagged command queue >> depth). > > I'm not sure what you mean by "also missing", since I have been spot-on > about disk writes potentially causing performance problems, and what you're > saying supports what I said before. This is something that I have studied > extensively. > > You are misinformed about SATA drives. Many do support NCQ, which is the > equivalent to TCQ on SAS/SCSI. The OS also maintains its cache and uses a > scheduler to try to optimize writes, usually doing a decent job at > maintaining a good rate of IOPs. Regardless of the NCQ/TCQ capability, the > same performance problem would exist, given heavy enough disk access. > > My comment about log writes listed them as an example of something that can > make a tick take longer than anticipated, along with plugins (and the game > itself). This is a valid example, but even if it were not valid, the overall > assertion stands. > >>> > I have no idea what baseline performance is in the context of a game >>> > server. >>> >>> The baseline performance in that case would be no background disk access. >> >> mlock()? Memory backed filesystem that doesn't cause faults? different >> drives? sockets? null? > > I think there might be a misunderstanding here. My example was that disk > write delays due to logging during periods of heavy disk writes are one > factor that I have seen lead to a performance problem and at the same time > cause FPS dips. The baseline performance case for that particular scenario > is very simple and as I described. I was not suggesting that there are no > other reasons for FPS dips, or suggesting a baseline performance description > for all scenarios. This is also a very small piece of what I said as a > whole.
Can't you keep your logs/ directory on some kind of ramdisk? _______________________________________________ To unsubscribe, edit your list preferences, or view the list archives, please visit: http://list.valvesoftware.com/mailman/listinfo/hlds_linux
