On Wed, 2008-01-30 at 09:38 +0100, Bart Van Assche wrote: > On Jan 30, 2008 12:32 AM, FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx> wrote: > > > > iSER has parameters to limit the maximum size of RDMA (it needs to > > repeat RDMA with a poor configuration)? > > Please specify which parameters you are referring to. As you know I > had already repeated my tests with ridiculously high values for the > following iSER parameters: FirstBurstLength, MaxBurstLength and > MaxRecvDataSegmentLength (16 MB, which is more than the 1 MB block > size specified to dd). the 1Mb block size is a bit of a red herring. Unless you've specifically increased the max_sector_size and are using an sg_chain converted driver, on x86 the maximum possible transfer accumulation is 0.5MB. I certainly don't rule out that increasing the transfer size up from 0.5MB might be the way to improve STGT efficiency, since at an 1GB/s theoretical peak, that's roughly 2000 context switches per I/O; however, It doesn't look like you've done anything that will overcome the block layer limitations. James - 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
