Pierre Ossman wrote: > I'm playing around with performance tuning my disk access, but there is > something limiting my bandwidth to the disks. I was hoping you could > help me determine what. > > My setup is a sil3132 controller, connected to a PMP with five disks > behind it. I'm using iostat to measure disk traffic and I'm using reads > via dd for testing. > > When I'm accessing a single disk, the bandwidth is 70 - 80 MiB/s. When > I access a second disk, the bandwidth is about 50 MiB/s/disk, and all > five results in 25 MiB/s/disk. In other words, something is limiting > things to about 100 MiB/s. Now the question is what that limiting > factor is. > > The PCIe bus can sustain 250 MiB/s, so even with overhead that should > be plenty. The SATA links are in theory 300 MiB/s, so that can't be it > either. The remaining factors are the controller and the multiplier > chip, and/or the way we access them. > > Tejun, what kind of throughput have you seen when you have been testing > the sil3132 and multipliers? That's the limit of sil3124/3132. Dunno why but you can't go over that. There's 3132-2 chip on the market. Maybe it's worth a try? -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
