Re: [PATCH V3 19/30] x86/sgx: Free up EPC pages directly to support large page ranges

Jarkko Sakkinen
2022-04-06T10:05:01Z

On Tue, 2022-04-05 at 10:25 -0700, Dave Hansen wrote:
> On 4/5/22 10:13, Reinette Chatre wrote:
> > > > +void sgx_direct_reclaim(void)
> > > > +{
> > > > +       if (sgx_should_reclaim(SGX_NR_LOW_PAGES))
> > > > +               sgx_reclaim_pages();
> > > > +}
> > > Please, instead open code this to both locations - not enough redundancy
> > > to be worth of new function. Causes only unnecessary cross-referencing
> > > when maintaining. Otherwise, I agree with the idea.
> > >
> > hmmm, that means the heart of the reclaimer (sgx_reclaim_pages()) would be
> > made available for direct use from everywhere in the driver. I will look into this.
>
> I like the change.  It's not about reducing code redundancy, it's about
> *describing* what the code does.  Each location could have:
>
>         /* Enter direct SGX reclaim: */
>         if (sgx_should_reclaim(SGX_NR_LOW_PAGES))
>                 sgx_reclaim_pages();
>
> Or, it could just be:
>
>         sgx_direct_reclaim();
>
> Which also provides a logical choke point to add comments, like:
>
> /*
>  * sgx_direct_reclaim() should be called in locations where SGX
>  * memory resources might be low and might be needed in order
>  * to make forward progress.
>  */
> void sgx_direct_reclaim(void)
> {
>         ...

Maybe cutting hairs but could it be "sgx_reclaim_direct"? Rationale
is easier grepping of reclaimer functions, e.g. when tracing.

BR, Jarkko