On Monday 10 January 2005 21:09, Guy wrote: > I use ext3 filesystems. No problems with performance (that I know of). > I have never tried any others. Reportedly, deleting a big (>2GB) file under XFS is way faster than under ext3, but I never verified this myself. I barely ever ran ext3, I went with my distros' default, which was Reiserfs. Deleting huge files is a special case though, so it does not make much sense to benchmark or tune for that. But in this special case it matters. > Do you think the performance difference of the various filesystems would > affect your PVR? Ehm, no. Well, not the raid-5 overhead at least. The FS helps the GUI being more 'snappy'. It has been reported that ext3 takes a real long time to delete huge files (up to several seconds or more) (unconfirmed by me). This is what a copy of a 5GB file and subsequent delete does on my system: -rw-r--r-- 1 root root 4909077650 Jan 10 04:43 file dozer:/mnt/store # time cp file away real 3m15.778s user 0m0.640s sys 0m45.230s dozer:/mnt/store # time rm away real 0m0.237s user 0m0.000s sys 0m0.020s (This was while the machine was idle, no recordings going on) But the machine IS starved for CPU and bus bandwidth; the cpu should be almost fully pegged with recording up to two simultaneous channels, compressing realtime(!) in mpeg4 from two cheap bttv cards (at 480x480 rez, 2600 Kbps). Therefore it is the fastest CPU I could afford back in last spring, an Athlon XP 2600. The machine is also overclocked from 200 FSB to 233, yielding a 38 MHz PCI bus. Strangely enough, despite there being 5 PCI cards, amongst which two disk I/O controllers, this seems to work just fine. It's been tested in-depth by recording shows daily for months and it crashes rarely ( meaning < once a month which is not too bad, considering ). Maybe the bigass Zalman copper CPU cooler and the 12cm fan hovering above it help there, too ;-) At the beginning it ran off a single 160GB disk, so when I switched to raid-5 I was very afraid that either the extra CPU load, the extra IRQ load or the bus bandwidth would saturate, thus killing performance. You see, the PCI bus is fairly loaded too, since not only does it have to handle the various ATA controllers, but two uncompressed videostreams from the TV cards as well. So all in all, the overhead of raid seems insignificant to me, or the code is very well optimized indeed :-) Maarten - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
