Hi Marc: 在 2016/12/2 17:35, Marc Zyngier 写道: > On 02/12/16 09:29, majun (Euler7) wrote: >> >> >> 在 2016/12/1 17:07, Marc Zyngier 写道: >>> On 01/12/16 07:45, Majun wrote: >>>> From: MaJun <majun...@huawei.com> >>>> >>>> For current ITS driver, two level table (indirect route) is enabled when >>>> the memory used >>>> for LPI route table over the limit(64KB * 2) size. But this function >>>> impact the >>>> performance of LPI interrupt actually because need more time to look up >>>> the table. >>> >>> Are you implying that your ITS doesn't have a cache to lookup the most >>> active devices, hence performing a full lookup on each interrupt? >> >> Our ITS chip has the cache with depth 64. But this seems not enough for some >> scenario,espeically on virtulization platform. > > Then I don't see how switching to to flat tables is going to improve > things. Can you share actual performance numbers? > Sorry, I run this code on EMU and have no actual performance numbers now.
Suppose there are 66 devices in system. As far as our chip concerned, there are always 2 devices can't benefit from cache fully when they report the interrupt. If i'm wrong, please correct me. Thanks Majun >>> Anyway, doing this as a DT quirk doesn't feel right. Please use the ITS >>> quirk infrastructure. >> >> If there is no other better solutions, I will do this. > > Thanks, > > M. >
