Re: [PATCH] sh: add support for TIF_NOTIFY_SIGNAL

[Jens Axboe <axboe@kernel.dk>]

On 1/1/21 8:30 AM, John Paul Adrian Glaubitz wrote:
> Hi Jens!
> 
> On 1/1/21 4:08 PM, Jens Axboe wrote:
>> On 1/1/21 7:06 AM, John Paul Adrian Glaubitz wrote:
>>> Is there away to test the change itself?
>>
>> The only user of TWA_SIGNAL, which uses TIF_NOTIFY_SIGNAL, so far is io_uring.
>> You need something that triggers deferred task_work processing, which is
>> basically anything that ends up being poll driven for data/space readiness.
>> Here's a small test app from the liburing test suite, that'll trigger it.
>>
>> If you install liburing, compile with:
>>
>> gcc -Wall -O2 -o socket-rw socket-rw.c -luring
>>
>> and run it without any arguments.
> 
> How long is this test supposed to run? It's already been running for some minutes
> on my 600 MHz machine.

It's supposed to finish very quickly:

axboe@p1 ~> time ./socket-rw                                                             0.000s

________________________________________________________
Executed in    1.10 millis    fish           external 
   usr time  888.00 micros  278.00 micros  610.00 micros 
   sys time   35.00 micros   35.00 micros    0.00 micros 

If it doesn't, can you try:

# echo 1 > /sys/kernel/debug/tracing/events/io_uring/enable

Then run the socket-rw app, and then do:

# cat /sys/kernel/debug/tracing/trace

and send that output? Might also be useful to include the strace
of the socket-rw just in case, so maybe run it ala

strace -o foo ./socket-rw

and include foo in the reply as well.

-- 
Jens Axboe