On 11/5/24 15:45, Terekhov, Mikhail wrote:
Internal Use - Confidential
From: Vincent Fu <vincentfu@xxxxxxxxx>
Sent: Tuesday, November 5, 2024 3:37 PM
To: Adam Horshack <horshack@xxxxxxxx>; fio@xxxxxxxxxxxxxxx
Subject: Re: blog post on fio write zeroes performance
When we added write zeroes support for the io_uring_cmd ioengine it was not on
our mind that the default behavior for fio is to scramble buffers. Basically these
patches just changed the opcode from a regular write to write zeroes.
You do have a good point that perhaps fio should be smart enough to avoid
touching the buffers when doing write zeroes.
Thanks for the feedback!
Vincent
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.
Vincent
