On Dienstag, 29. September 2020 15:49:42 CEST Vivek Goyal wrote: > > Depends on what's randomized. If read chunk size is randomized, then yes, > > you would probably see less performance increase compared to a simple > > 'cat foo.dat'. > > We are using "fio" for testing and read chunk size is not being > randomized. chunk size (block size) is fixed at 4K size for these tests.
Good to know, thanks! > > If only the read position is randomized, but the read chunk size honors > > iounit, a.k.a. stat's st_blksize (i.e. reading with the most efficient > > block size advertised by 9P), then I would assume still seeing a > > performance increase. > > Yes, we are randomizing read position. But there is no notion of looking > at st_blksize. Its fixed at 4K. (notice option --bs=4k in fio > commandline). Ah ok, then the results make sense. With these block sizes you will indeed suffer a performance issue with 9p, due to several thread hops in Tread handling, which is due to be fixed. Best regards, Christian Schoenebeck
