On Tue, 5 Nov 2024 at 21:33, Vincent Fu <vincentfu@xxxxxxxxx> wrote: > > On 11/5/24 15:45, Terekhov, Mikhail wrote: > > > > Does it mean that in the regular case (not write zeroes) fio spends significant time scrambling buffers and IO performance is lower than it could be? > > > > Regards, > > Mikhail > > For regular writes on contemporary devices the time that fio spends > scrambling buffers is small compared to the device response time. > > However, if you want the absolute highest write performance or are > really pushing the limits with a device, it might be worth running the > job with zero_buffers or scramble_buffers=0 to see what difference it makes. It's worth noting that even in the "not write zeros dedicated command" case some devices (or things in the I/O path like filesystems etc.) can detect or compress buffers of zeros and thus are able to achieve (unrealistic) higher speeds that they cannot reach when "real" data is used... -- Sitsofe
