Re: [????] Re: [PATCH][v2] RDMA/core: Prevent soft lockup during large user memory region cleanup

[Jason Gunthorpe <jgg@ziepe.ca>]

On Wed, Nov 19, 2025 at 02:03:20AM +0000, Li,Rongqing wrote:
> > > Fix soft lockup issues by incorporating cond_resched() calls within
> > > __ib_umem_release(), and this SG entries are typically grouped in 2MB
> > > chunks on x86_64, adding cond_resched() should has minimal
> > performance
> > > impact.
> > 
> > This is not true, I think this should have been more careful to only resched
> > after larger groupings.. How much slower did you make normal 4k unpins??
> > 
> > Jason
> 
> 
> I don't see this as a issue for several reasons. First, this code
> path is not performance-critical. 

Yes it is!

> Second, the number of cond_resched
> calls added by this modification is identical to what was introduced
> in commit 928da37a229f3444, 

No its not! That loop does entire batches of pages into a PAGE_SIZE
memory buffer, this does it for every single 4k page.

> any problems. Third, as seen in commit 16c610162d1f1c, the
> cond_resched call rate was reduced to once every 16 packets - our
> current frequency remains well below this commit.

I don't know what that has to do with anything here

Jason