发件人：Matthew Wilcox <willy@xxxxxxxxxxxxx> 发送日期：2020-04-21 22:36:09 收件人："赵军奎" <bernard@xxxxxxxx> 抄送人：Christoph Lameter <cl@xxxxxxxxx>,Pekka Enberg <penberg@xxxxxxxxxx>,David Rientjes <rientjes@xxxxxxxxxx>,Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>,Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>,linux-mm@xxxxxxxxx,linux-kernel@xxxxxxxxxxxxxxx,opensource.kernel@xxxxxxxx 主题：Re: Re: [PATCH V2] kmalloc_index optimization(code size & runtime stable)>On Tue, Apr 21, 2020 at 07:55:03PM +0800, 赵军奎 wrote: >> Sure, i just received some kbuild compiler error mails and prompt me to do something? >> I don`t know why this happened, so i update the patch again. > >Don't. The patch has been NACKed, so there's no need to post a v2. > >If you want to do something useful, how about looking at the effect >of adding different slab sizes? There's a fairly common pattern of >allocating things which are a power of two + a header. So it may make >sense to have kmalloc caches of 320 (256 + 64), 576 (512 + 64) and 1088 >(1024 + 64). I use 64 here as that's the size of a cacheline, so we >won't get false sharing between users. > >This could save a fair quantity of memory; today if you allocate 512 + >8 bytes, it will round up to 1024. So we'll get 4 allocations per 4kB >page, but with a 576-byte slab, we'd get 7 allocations per 4kB page. >Of course, if there aren't a lot of users which allocate memory in this >range, then it'll be a waste of memory. On my laptop, it seems like >there might be a decent amount of allocations in the right range: > >kmalloc-2k 3881 4384 2048 16 8 : tunables 0 0 0 : sla >bdata 274 274 0 >kmalloc-1k 6488 7056 1024 16 4 : tunables 0 0 0 : slabdata 441 441 0 >kmalloc-512 7700 8256 512 16 2 : tunables 0 0 0 : slabdata 516 516 0 > >Now, maybe 576 isn't quite the right size. Need to try it on a variety >of configurations and find out. Want to investigate this? This looks like a great idea! Maybe I can do some research on our mobile phone products， and see how the original size of kmalloc is distributed. This may be useful as a reference to provide a flexible configuration method. Thank you very much for your sharing. Regards, Bernard
