On Fri, Dec 28, 2018, 1:25 AM matthew green <m...@eterna.com.au wrote: > > Of course larger transfers would also mitigate the overhead for each I/O > > operation, but we already do several Gigabyte/s with 64k transfers and > > filesystem I/O tends to be even smaller. > > yes - the benefits will be in the 0-10% range for most things. it > will help, but only a fairly small amount, most of us won't notice. > > i've seen peaks of 1.4GB/s with an nvme(4) device with ffs on top. >
I've seen 3.3GB/s of 128k-512k transfers on FreeBSD off of nvme, but that's mostly video. It seems to be limited there not so much by transfer size, but by the ability to queue transactions. We see <1% by raising MAXPHYS to 1MB over the default 128k there. Warner >
