On Thu, May 15, 2008 at 3:12 AM, Cameron Harr <charr@xxxxxxxxxxxx> wrote: > Hi, I've been trying to compare performances between iSer and srpt and > am getting mixed results where iSer wins for IOPs and srpt wins for some > streaming b/w tests. I've tested with iozone, spew and FIO, and IOP > numbers are always higher on iSer. My problem though is that I'm a > little suspicious of some of the iSer numbers and whether they are > really using Direct IO. For example, you'll see below in some of my FIO > results that I'm getting a write B/W of 799.1 MB/s at one point. That's > way above what I can get natively on the device (~650 MB/s DIO) and is > more along the lines of buffered IO. If the IOP numbers are also using > some kind of caching, that could possibly taint them also. Does anyone > know if specifying DIO will really bypass all buffers or if something is > getting cached in the agents (iscsi, tgtd)? > > > FIO > --------------- iSer 1----iSer 2----SRPT 1----SRPT 2- > RBW (MB/s) 565.3 836.5 622.0 581.7 > Read IOPs 63488.1 68053.8 5335.6 5446.1 > WBW (MB/s) 799.1 737.7 589.5 594.4 > Write IOPs 79086.6 80005.7 33884.6 34058.6 > > > Thanks much, > Cameron > Your question should be posted on linux-scsi. See the following link that explains about DIO http://tldp.org/HOWTO/SCSI-Generic-HOWTO/dio.html Please check with sgp_dd to avoid any caching. Thanks, Eli -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
