Messages in this thread | | | Date | Fri, 20 May 2022 17:39:40 +0200 | From | "Jason A. Donenfeld" <> | Subject | Re: [PATCH v4 0/3] random: convert to using iters, for Al Viro |
| |
Hi Jens,
On Fri, May 20, 2022 at 09:34:46AM -0600, Jens Axboe wrote: > On 5/20/22 9:25 AM, Jason A. Donenfeld wrote: > > Hi Jens, > > > > On Fri, May 20, 2022 at 11:44:56AM +0200, Jason A. Donenfeld wrote: > >> Jens Axboe (3): > >> random: convert to using fops->read_iter() > >> random: convert to using fops->write_iter() > >> random: wire up fops->splice_{read,write}_iter() > > > > FYI, this series makes reads from /dev/urandom slower, from around 616 > > MiB/s to 598 MiB/s on my system. That seems rather unfortunate. > > How reproducible is that? That seems like a huge difference for the > change. How big are the reads?
Fairly reproducible. Actually, if anything, it reproduces consistently with worst results; I chose the most favorable ones for the new code. This isn't any fancy `perf` profiling, but just running:
$ pv /dev/urandom > /dev/null
From looking at strace, the read size appears to be 131072.
Jason
| |