>> @@ -3217,6 +3217,10 @@ static int proc_pid_ksm_stat(struct seq_file *m, struct pid_namespace *ns, >> seq_printf(m, "ksm_zero_pages %lu\n", mm->ksm_zero_pages); >> seq_printf(m, "ksm_merging_pages %lu\n", mm->ksm_merging_pages); >> seq_printf(m, "ksm_process_profit %ld\n", ksm_process_profit(mm)); >> + seq_printf(m, "KSM_mergeable: %s\n", >> + test_bit(MMF_VM_MERGEABLE, &mm->flags) ? "yes" : "no"); > >All it *currently* means is "we called __ksm_enter()" once. It does not >mean that KSM is still enabled for that process and that any VMA would >be considered for merging. > >I don't think we should expose this. > >That information can be more reliably had by looking at > >"/proc/pid/smaps" and looking for "mg". > >Which tells you exactly if any VMA (and which) is currently applicable >to KSM. > > >> + seq_printf(m, "KSM_merge_any: %s\n", >> + test_bit(MMF_VM_MERGE_ANY, &mm->flags) ? "yes" : "no"); > >This makes more sense to export. It's the same as reading >prctl(PR_GET_MEMORY_MERGE). > >The man page [1] calls it simply "KSM has been enabled for this >process", so process-wide KSM compared to per-VMA KSM. > >"KSM_enabled:" > >*might* be more reasonable in the context of PR_SET_MEMORY_MERGE. > >It wouldn't tell though if KSM is enabled on the system, though. > I agree it. But I hope admistrators can tell if the process enabled KSM-scan by madvise or prctl. At this point, only "/proc/pid/smaps" is not enough. So can we add a item "KSM_enabled" which has three value as follows? 1) "prctl": KSM has been fully enabled for this process. 2) "madvise": KSM has been enabled on parts of VMA for this process. 3) "never": KSM has been never enabled for this process. Just refer to the semantics of '/sys/kernel/mm/transparent_hugepage/enabled'
