Martin, I agree with you 100% that dd does not measure proper performance (and that /dev/zero is not a very good test).
Hence I'm asking.. I know that I get fast copy/write speeds on the btrfs volume from real life situations, but NOT with samba. So, is there something I can do to test why samba is slow transferring from win7 to a samba share on a btrfs volume? Thank you, On Fri, Jul 20, 2012 at 7:24 PM, Remco Hosman <re...@hosman.xs4all.nl> wrote: > > Op 20-7-2012 11:15, Martin Steigerwald schreef: > >> Am Freitag, 20. Juli 2012 schrieb Shavi N: >> >>> On Fri, Jul 20, 2012 at 12:19 AM, Martin Steigerwald >>> >>> <mar...@lichtvoll.de> wrote: >>>> >>>> Am Donnerstag, 19. Juli 2012 schrieb Shavi N: >>>>> >>>>> Hi, >>>> >>>> Hi Shavi, >>>> >>>>> Thanks. >>>>> >>>>> This is the output: >>>>> btrfs: >>>>> $ dd if=/dev/zero of=/mnt/shared/misc/temp_file bs=1M count=1400 >>>>> 1400+0 records in >>>>> 1400+0 records out >>>>> 1468006400 bytes (1.5 GB) copied, 1.56841 s, 936 MB/s >>>>> >>>>> ext4: >>>>> $ dd if=/dev/zero >>>>> of=/mnt/500/VirutalBox_VMs/thor/thor-data/temp_file bs=1M >>>>> count=1400 >>>>> 1400+0 records in >>>>> 1400+0 records out >>>>> 1468006400 bytes (1.5 GB) copied, 4.98993 s, 294 MB/s >>>> >>>> Did you actually read and understand my mail? >>>> >>>> Do you really think that your local disks is/are yielding that >>>> transferrate? (Unless you are using BTRFS RAID 0/10 on lots of >>>> disks.) >>> >>> Yes I read and understood your email. my btrfs volume consists of 11 >>> HDD's. I was very surprised with that result myself... >> >> I think that you did not understood it. Why? Your dd tests where without >> conv=fsync – did you even try with conv=fsync to compare results? >> >> 11 really fast 15000rpm FC / SAS disks could possibly do 936 MB/s. But >> regular 7200rpm SATA disks depending to the on disk location might be as >> slow as 40-50 MB/s – just try fio disk-zone-profile on one if you do not >> believe this – and then even with 11 disks 936 MB/s is out of reach. > > > My BTRFS array consists of 5 WD Green 2T disks. each of them goes a bit over > 100MB/sec on sequential read/write. > > Remco > > >> And then speed depends on the BTRFS RAID level as well. And if BTRFS is >> using compression then testing with zeros is bogus anyway. >> >> Also its questionable whether CIFS will use 1 MiB blocksizes. It might be >> using it in most current kernels, since there have been some adaption – >> but I am not sure ATM whether they have been for reads or writes, they >> have not been for both, check wsize, rsize or similar named option >> maximums –, but thats also a point where to look. >> >> But then are the files that you transfer there that big at all? And what >> is the accesses pattern? Virtualbox VM images are usually not written >> sequentially to, so you need a random I/O workload. >> >> I do think in order to get more close to the possible reason of Samba >> slowness with BTRFS a simple dd test won´t help one bit. Even the >> conv=fsync case will most likely not be testing the workload that Samba >> exercises on the local disks. >> >> Some fio random I/O workload or dbench or filebench workload might be much >> closer. >> >> I think currently you are measuring something that has almost nothing to >> do with your real workload. >> >> Ciao, > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
