Re: [PATCH] binder: Use kmem_cache for binder_thread

Christian Brauner
2019-08-30T12:14:43Z

On Fri, Aug 30, 2019 at 08:38:51AM +0200, Greg KH wrote:
> On Thu, Aug 29, 2019 at 05:27:22PM +0200, Christian Brauner wrote:
> > On Thu, Aug 29, 2019 at 09:53:59AM -0400, Joel Fernandes wrote:
> > > On Thu, Aug 29, 2019 at 08:42:29AM +0200, Greg KH wrote:
> > > > On Thu, Aug 29, 2019 at 01:49:53PM +0800, Peikan Tsai wrote:
> > > [snip]
> > > > > The allocated size for each binder_thread is 512 bytes by kzalloc.
> > > > > Because the size of binder_thread is fixed and it's only 304 bytes.
> > > > > It will save 208 bytes per binder_thread when use create a kmem_cache
> > > > > for the binder_thread.
> > > >
> > > > Are you _sure_ it really will save that much memory? You want to do
> > > > allocations based on a nice alignment for lots of good reasons,
> > > > especially for something that needs quick accesses.
> > >
> > > Alignment can be done for slab allocations, kmem_cache_create() takes an
> > > align argument. I am not sure what the default alignment of objects is
> > > though (probably no default alignment). What is an optimal alignment in your
> > > view?
> >
> > Probably SLAB_HWCACHE_ALIGN would make most sense.
>
> This isn't memory accessing hardware, so I don't think it would, right?

I was more thinking of cacheline bouncing under contention. But maybe
that's not worth it in this case...