From: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Date: 2020-04-17 11:23:54 To: Bernard Zhao <bernard@xxxxxxxx> Cc: 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,kernel@xxxxxxxx Subject: Re: [PATCH] kmalloc_index optimization(code size & runtime stable)>On Thu, Apr 16, 2020 at 07:03:30PM -0700, Bernard Zhao wrote: >> kmalloc_index inline function code size optimization and runtime >> performance stability optimization. After optimization, the function >> kmalloc_index is more stable, the size will never affecte the function`s >> execution efficiency. >> And follow test data shows that the performance of new optimization >> exceeds the original algorithm when applying for more than 512 Bytes >> (include 512B).And new optimization runtime is more stable than before. > >That's all very well and good, but the vast majority of allocations >are less than 512 bytes in size! Your numbers show that on average, >this patch makes the kernel slower!>This is indeed the case, the new algorithm is stable at a time level, butthere is a certain performance loss for relatively small memory(little than 512).I will continue to pay attention to this part later. Thanks.>> size time/Per 100 million times.us >> old fun new fun with optimise >> 8 203777 241934 >> 16 245611 409278 >> 32 236384 408419 >> 64 275499 447732 >> 128 354909 416439 >> 256 360472 406598 >> 512 431072 409168 >> 1024 463822 407401 >
