On May 12, 2010, at 10:48 AM, Jeffrey Altman wrote: > On 5/11/2010 1:01 PM, Hartmut Reuter wrote: >> >> I have now ported AFS/RXOSD to 1.5.74. >> I am testing the client against servers running 1.4.12-osd. >> >> My client configuration is memcache with chunksize 18 (256K). >> Writing to the fileserver and also to the rxosd is as fast as with the 1.4.12 >> client (I am testing on my laptop with the whole test-cell in the laptop, so >> 30 >> MB/s is already an acceptable value). >> >> But reading large files is terribly slow (~ 1 MB/s). With the 1.4.12 client >> read >> and write have about the same speed. >> >> with rxdebug -peer -long I can also see that some times in the rtt the >> fileserver or rxosd see is growing up to several seconds and then again going >> down to a ms. So there seems to be something strange in the rx-layer. >> It also shows a lot of resends (about 1 %). >> >> Any idea? >> >> Hartmut > > The first thing that comes to mind is that we found the rx library was > dropping packets on the floor under high load. This was fixed in the > 1.5.74 release but has not been fixed in the 1.4.12 release.
Any feel for the net effect on throughput? Is the improvement significant enough to consider backporting to 1.4.13? > The 1.5.74 client should be able to put more load on the file server > as it does a much better job of efficiently reading from the page > cache. I don't understand the connection here. Hartmut seems to be saying that a 1.4.12osd client reading from a 1.4.12osd server runs 30x faster than a 1.5.74osd client reading from a 1.4.12osd server. Improvements in 1.5.74 client-side reading of the page cache shouldn't have any affect - presumably one is only reading the file because it isn't in page or disk cache. 30-fold is a pretty big number, too. Steve _______________________________________________ OpenAFS-devel mailing list [email protected] https://lists.openafs.org/mailman/listinfo/openafs-devel
