Messages in this thread | | | Date | Sat, 14 Jul 2001 01:49:36 +1000 | From | Andrew Morton <> | Subject | Re: 2x Oracle slowdown from 2.2.16 to 2.4.4 |
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"Jeffrey W. Baker" wrote: > > > ... > > ext2: Throughput 2.71849 MB/sec (NB=3.39812 MB/sec 27.1849 MBit/sec) > > ext3: Throughput 12.3623 MB/sec (NB=15.4529 MB/sec 123.623 MBit/sec) > > > > ext3 patches are at http://www.uow.edu.au/~andrewm/linux/ext3/ > > > > The difference will be less dramatic with large, individual writes. > > This is a totally transient effect, right? The journal acts as a faster > buffer, but if programs are writing a lot of data to the disk for a very > long time, the throughput will eventually be throttled by writing the > journal back into the filesystem.
It varies a lot with workload. With large writes such as 'iozone -s 300m -a -i 0' it seems about the same throughput as ext2. It would take some time to characterise fully.
> For programs that write in bursts, it looks like a huge win!
yes - lots of short writes (eg: mailspools) will benefit considerably. The benefits come from the additional merging and sorting which can be performed on the writeback data.
I suspect some of the dbench benefit comes from the fact that the files are unlinked at the end of the test - if the data hasn't been written back at that time the buffers are hunted down and zapped - they *never* get written.
If anyone wants to test sync throughput, please be sure to use 0.9.3-pre - it fixes some rather sucky behaviour with large journals.
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