On Tue, 22 Jan 2008 14:33:13 +0300 Vladislav Bolkhovitin <vst@xxxxxxxx> wrote: > FUJITA Tomonori wrote: > > The big problem of stgt iSER is disk I/Os (move data between disk and > > page cache). We need a proper asynchronous I/O mechanism, however, > > Linux doesn't provide such and we use a workaround, which incurs large > > latency. I guess, we cannot solve this until syslets is merged into > > mainline. > > Hmm, SCST also doesn't have ability to use asynchronous I/O, but that > doesn't prevent it from showing good performance. I don't know how SCST performs I/Os, but surely, in kernel space, you can performs I/Os asynchronously. Or you use an event notification mechanism with multiple kernel threads performing I/Os synchronously. Xen blktap has the same problem as stgt. IIRC, Xen mainline uses a kernel patch to add a proper event notification to AIO though redhat uses the same workaround as stgt instead of applying the kernel patch. - 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
