> On Thu, May 05, 2016 at 07:44:29PM +0000, Stephen Bates wrote: > > I am very interested in seeing this added. There are use cases involving > super-low latency (non-NAND based) NVMe devices and they want the > fastest possible IO response times for ALL IO to that device. They also have > no desire to wait for the new system calls and glibc updates needed to tie > their applications into polling or to rewrite their applications to avail of those > new calls. I have done some testing on Jon's "big hammer" and it seems to > work well for this use case and applied cleanly against v4.6-rc6. > > Let's get the driver for those devices merged first, and if you can provide > numbers that it's worth it we can add a tweak to always enable polling from > the driver for those devices. Christoph, this is a DRAM based NVMe device, the code for polling in NVMe was merged in 4.5 right? We are using the inbox NVMe driver. Here is some performance data: QD=1, single thread, random 4KB reads Polling Off: 12us Avg / 40us 99.99% ; Polling On: 9.5us Avg / 25us 99.99% Both the average and 99.99% reduction are of interest. Cheers Stephen -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
