On Wed, 2025-01-01 at 16:15 +0000, Karim Manaouil wrote: > On Wed, Jan 01, 2025 at 05:20:01PM +0200, Nadav Amit wrote: > > > > > > On 01/01/2025 6:42, Rik van Riel wrote: > > > Fixed for the next version. > > > > Thanks Rik, > > > > Admittedly, I don't feel great about my overall last review - it > > mostly > > focused on style and common BKMs. > > > > I still don't quite get the entire logic. To name one thing that I > > don't > > understand: why do we need broadcast_asid_list and the complicated > > games of > > syncing it with broadcast_asid_used. Why wouldn't > > broadcast_asid_used > > suffice? > > If I uderstand correctly from Rik's patch, I think the list is needed > to > save the flush for only when we run out of the ASID space (wrap > around). > Without the list, whenever the ASID bit is cleared, you also have to > flush > the TLBs. That's exactly it. The list will only contain processes that are active on multiple CPUs, and hit a TLB flush "at the right moment" to be assigned a broadcast ASID, which will be true for essentially every process that does a lot of TLB flushes and is long lived. However, something like a kernel build has lots of short lived, single threaded processes, for which we should not be using broadcast TLB flushing, and which will not need to remove themselves from the list at exit time. -- All Rights Reversed.
