2024-01-12 13:02:15

by Thomas Gleixner

[permalink] [raw]
Subject: Re: [PATCH] xfs: explicitly call cond_resched in xfs_itruncate_extents_flags

On Fri, Jan 12 2024 at 07:27, Dave Chinner wrote:

Cc: Ankur

> On Thu, Jan 11, 2024 at 08:52:22PM +0800, Jian Wen wrote:
>> On Thu, Jan 11, 2024 at 5:38 AM Dave Chinner <[email protected]> wrote:
>> > IOWs, this is no longer considered an acceptible solution by core
>> > kernel maintainers.
>> Understood. I will only build a hotfix for our production kernel then.
>
> Yeah, that may be your best short term fix. We'll need to clarify
> what the current policy is on adding cond_resched points before we
> go any further in this direction.

Well, right now until the scheduler situation is sorted there is no
other solution than to add the cond_resched() muck.

> Thomas, any update on what is happening with cond_resched() - is
> there an ETA on it going away/being unnecessary?

Ankur is working on that...


2024-01-23 07:02:39

by Ankur Arora

[permalink] [raw]
Subject: Re: [PATCH] xfs: explicitly call cond_resched in xfs_itruncate_extents_flags

[ Missed this email until now. ]

Thomas Gleixner writes:

>On Fri, Jan 12 2024 at 07:27, Dave Chinner wrote:
>
>Cc: Ankur
>
> > On Thu, Jan 11, 2024 at 08:52:22PM +0800, Jian Wen wrote:
> >> On Thu, Jan 11, 2024 at 5:38 AM Dave Chinner <[email protected]> wrote:
> >> > IOWs, this is no longer considered an acceptible solution by core
> >> > kernel maintainers.
> >> Understood. I will only build a hotfix for our production kernel then.
> >
> > Yeah, that may be your best short term fix. We'll need to clarify
> > what the current policy is on adding cond_resched points before we
> > go any further in this direction.
>
> Well, right now until the scheduler situation is sorted there is no
> other solution than to add the cond_resched() muck.
>
> > Thomas, any update on what is happening with cond_resched() - is
> > there an ETA on it going away/being unnecessary?
>
> Ankur is working on that...

Yeah, running through a final round of tests before sending out the series.

Dave, on the status of cond_resched(): the work on this adds a new scheduling
model (as Thomas implemented in his PoC) undwer which cond_resched() would
basically be a stub.

However, given that other preemption models continue to use cond_resched(),
we would need to live with cond_resched() for a while -- at least while
this model works well enough under a wide enough variety of loads.

Thanks
Ankur