On Fri, Aug 30, 2019 at 02:59:01AM +0800, Peikan Tsai 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. > > > > Agree. Thanks for yours comments and suggestions. > I'll put SLAB_HWCACHE_ALIGN it in patch v2. > > > > > > > > Did you test your change on a system that relies on binder and find any > > > > speed improvement or decrease, and any actual memory savings? > > > > > > > > If so, can you post your results? > > > > > > That's certainly worth it and I thought of asking for the same, but spoke too > > > soon! > > > > Yeah, it'd be interesting to see what difference this actually makes. > > > > Christian > > I tested this change on an Android device(arm) with AOSP kernel 4.19 and > observed > memory usage of binder_thread. But I didn't do binder benchmark yet. > > On my platform the memory usage of binder_thread reduce about 90 KB as > the > following result. > nr obj obj size total > before: 624 512 319488 bytes > after: 728 312 227136 bytes You have more objects??? _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
