Re: [PATCH] block: reexpand iov_iter after read/write

[Jens Axboe <axboe@kernel.dk>]

On 5/6/21 3:08 PM, Al Viro wrote:
> On Thu, May 06, 2021 at 01:15:01PM -0600, Jens Axboe wrote:
> 
>> Attached output of perf annotate <func> for that last run.
> 
> Heh...  I wonder if keeping the value of iocb_flags(file) in
> struct file itself would have a visible effect...

A quick hack to get rid of the init_sync_kiocb() in new_sync_write() and
just eliminate the ki_flags read in eventfd_write(), as the test case is
blocking. That brings us closer to the ->write() method, down 7% vs the
previous 10%:

Executed in  468.23 millis    fish           external
   usr time   95.09 millis  114.00 micros   94.98 millis
   sys time  372.98 millis   76.00 micros  372.90 millis

Executed in  468.97 millis    fish           external
   usr time   91.05 millis   89.00 micros   90.96 millis
   sys time  377.92 millis   69.00 micros  377.85 millis

-- 
Jens Axboe