On August 29, 2019 2:59:01 PM EDT, Peikan Tsai <peikantsai@xxxxxxxxx> 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 And add this to the changelog as well. Curious- why is nrobj higher with the patch? Please don't use my reviewed-by tag yet and I will review the new patch and provide tag separately. Thank you. -- Sent from my Android device with K-9 Mail. Please excuse my brevity. _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
