On Wed, 9 Dec 2020 01:56:14 +0000 Vladimir Oltean wrote:
> On Mon, Dec 07, 2020 at 05:09:37PM -0800, Jakub Kicinski wrote:
> > > + ocelot->owq = alloc_ordered_workqueue("ocelot-owq", WQ_MEM_RECLAIM);
> >
> > Why MEM_RECLAIM ?
>
> Ok, fine, I admit, I copied it.
>
> After reading the documentation a bit more thoroughly, I am still as
> clear about the guidelines as before. The original logic was, I am
> allocating a memory area and then freeing it from the work item. So it
> must be beneficial for the kernel to want to flush this workqueue during
> the memory reclaim process / under memory pressure, because I am doing
> no memory allocation, and I am also freeing some memory in fact.
>
> The thing is, there are already a lot of users of WQ_MEM_RECLAIM. Many
> outside of the filesystem/block subsystems. Not sure if all of them
> misuse it, or how to even tell which one constitutes a correct example
> of usage for WQ_MEM_RECLAIM.
Agreed, I wasn't 100% sure either.
I double checked with Tejun, he says it's only needed if the work
queue is directly used in memory reclaim paths, like writing pages
out to swap and such.
