Linus Torvalds <torva...@linux-foundation.org> writes: > On Wed, Feb 27, 2019 at 5:19 PM Huang, Ying <ying.hu...@intel.com> wrote: >> >> So I think in the heavily contended situation, we should put the fields >> accessed by rwsem holder in a different cache line of rwsem. But in >> un-contended situation, we should put the fields accessed in rwsem >> holder and rwsem in the same cache line to reduce the cache footprint. >> The requirement of un-contended and heavily contended situation is >> contradicted. > > Generally, we should strive to optimize for the uncontended state. > > The performance profile of a contended state tends to be very > different, and the actual solution tends to be to try really hard to > just avoid contention to begin with. > > I think we've gotten to the point where we have very few real loads > that show lock contention on a kernel level. And when people do find > loads that cause contention, we should try really hard to fix the > locking rather than try to then treat the symptom of contention. > > So on the whole, aim to make the uncontended case go fast, at least to > a first approximation.
Sounds reasonable! Thanks for clarification! Best Regards, Huang, Ying > Linus
