On 06/27/2012 10:39 AM, Konrad Rzeszutek Wilk wrote: > On Wed, Jun 27, 2012 at 08:12:56AM -0700, Dan Magenheimer wrote: >>> From: Minchan Kim [mailto:minchan@xxxxxxxxxx] >>> Subject: Re: [PATCH 3/3] x86: add local_tlb_flush_kernel_range() >>> >>> Hello, >>> >>> On 06/27/2012 03:14 PM, Alex Shi wrote: >>> >>>> On 06/27/2012 01:53 PM, Minchan Kim wrote: >>>> >>>>> On 06/26/2012 01:14 AM, Seth Jennings wrote: >>>>> >>>>>> This patch adds support for a local_tlb_flush_kernel_range() >>>>>> function for the x86 arch. This function allows for CPU-local >>>>>> TLB flushing, potentially using invlpg for single entry flushing, >>>>>> using an arch independent function name. >>>>>> >>>>>> Signed-off-by: Seth Jennings <sjenning@xxxxxxxxxxxxxxxxxx> >>>>> >>>>> >>>>> Anyway, we don't matter INVLPG_BREAK_EVEN_PAGES's optimization point is 8 or something. >>>> >>>> >>>> Different CPU type has different balance point on the invlpg replacing >>>> flush all. and some CPU never get benefit from invlpg, So, it's better >>>> to use different value for different CPU, not a fixed >>>> INVLPG_BREAK_EVEN_PAGES. >>> >>> I think it could be another patch as further step and someone who are >>> very familiar with architecture could do better than. >>> So I hope it could be merged if it doesn't have real big problem. >>> >>> Thanks for the comment, Alex. >> >> Just my opinion, but I have to agree with Alex. Hardcoding >> behavior that is VERY processor-specific is a bad idea. TLBs should >> only be messed with when absolutely necessary, not for the >> convenience of defending an abstraction that is nice-to-have >> but, in current OS kernel code, unnecessary. > > At least put a big fat comment in the patch saying: > "This is based on research done by Alex, where ... I can do this. -- Seth -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>