On Tue, Aug 31, 2021 at 06:45:46PM +0200, Sebastian Andrzej Siewior wrote: > On 2021-08-05 17:00:19 [+0100], Mel Gorman wrote: > > mm/vmstat.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 48 insertions(+) > > The version in RT also covered the functions > __count_vm_event() > __count_vm_events() > > in include/linux/vmstat.h. Were they dropped by mistake or on purpose? > Sorry for the long delay, this got lost in a mess of mail. It was dropped on purpose and I tried to explain why in the changelog This patch differs from the preempt-rt version where __count_vm_event and __count_vm_events are also protected. The counters are explicitly "allowed to be to be racy" so there is no need to protect them from preemption. Only the accurate page stats that are updated by a read-modify-write need protection. This patch also differs in that a preempt_[en|dis]able_rt helper is not used. As vmstat is the only user of the helper, it was suggested that it be open-coded in vmstat.c instead of risking the helper being used in unnecessary contexts. Does that answer your question? -- Mel Gorman SUSE Labs
