Re: [PATCH v2 0/1] Fix slow loading problem introduced by 887f98f0d

[Gary Lin]

On Tue, Sep 13, 2022 at 11:16:19AM +0800, Gary Lin via Grub-devel wrote:
> On Tue, Sep 13, 2022 at 01:49:51AM +0800, Zhang Boyang wrote:
> > Hi,
> > 
> > This patch should probably fix the slow loading problem introduced by
> > 887f98f0db43 (mm: Allow dynamically requesting additional memory
> > regions).
> > 
> > Although I'm not against increasing default heap size, simply increasing
> > heap size may not fully fix the problem. I think the root cause is disk
> > caches are always invalidated when almost every malloc() after default
> > heap size is exhausted.
> > 
> Deferring disk cache invalidation may not be a good idea because disk
> cache is not mission-critical, so it's reasonable to invalidate the
> caches to squeeze more memory blocks. The real question is still about
> the default heap size. The memory allocation path is not cheap and it
> should be avoided as much as possible. If the first allocated heap can
> fulfill the most cases, then users won't be bothered by the performance
> drop that much.
> 
I see your point now. Instead of keeping a minimal heap, your patch
maximizes the heap to a certain point and then invalidates disk caches
to sequeeze the last memory pages. This certainly benefits the
performance.

Gary Lin

> Gary Lin
> 
> > However, I havn't reproduced the problem, so I haven't tested my patch.
> > I would appreciate if someone can test this patch.
> > 
> > Changes in V2:
> >   Use GRUB_MM_HEAP_GROW constant instead of hardcoding 0x100000.
> >   Renamed "rsize" to "grow".
> >   Check "grow" against sanity limits.
> > 
> > Best Regards,
> > Zhang Boyang 
> > 
> > 
> > 
> 
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> https://lists.gnu.org/mailman/listinfo/grub-devel