Messages in this thread | | | Date | Mon, 11 Feb 2013 15:25:22 +0530 | From | Srikar Dronamraju <> | Subject | Re: [PATCH 7/7] uprobes/perf: Avoid uprobe_apply() whenever possible |
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* Oleg Nesterov <oleg@redhat.com> [2013-02-04 20:03:05]:
> uprobe_perf_open/close call the costly uprobe_apply() every time, > we can avoid it if: > > - "nr_systemwide != 0" is not changed. > > - There is another process/thread with the same ->mm. > > - copy_proccess() does inherit_event(). dup_mmap() preserves the > inserted breakpoints. > > - event->attr.enable_on_exec == T, we can rely on uprobe_mmap() > called by exec/mmap paths. > > - tp_target is exiting. Only _close() checks PF_EXITING, I don't > think TRACE_REG_PERF_OPEN can hit the dying task too often. > > Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> --- > kernel/trace/trace_uprobe.c | 42 ++++++++++++++++++++++++++++++++++++------ > 1 files changed, 36 insertions(+), 6 deletions(-) > > diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c > index 1114619..e4aab34 100644 > --- a/kernel/trace/trace_uprobe.c > +++ b/kernel/trace/trace_uprobe.c > @@ -677,30 +677,60 @@ __uprobe_perf_filter(struct trace_uprobe_filter *filter, struct mm_struct *mm) > return false; > } > > +static inline bool > +uprobe_filter_event(struct trace_uprobe *tu, struct perf_event *event) > +{ > + return __uprobe_perf_filter(&tu->filter, event->hw.tp_target->mm); > +} > + > static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event) > { > + bool done; > + > write_lock(&tu->filter.rwlock); > - if (event->hw.tp_target) > + if (event->hw.tp_target) { > + /* > + * event->parent != NULL means copy_process(), we can avoid > + * uprobe_apply(). current->mm must be probed and we can rely > + * on dup_mmap() which preserves the already installed bp's. > + * > + * attr.enable_on_exec means that exec/mmap will install the > + * breakpoints we need. > + */ > + done = tu->filter.nr_systemwide || > + event->parent || event->attr.enable_on_exec || > + uprobe_filter_event(tu, event); > list_add(&event->hw.tp_list, &tu->filter.perf_events); > - else > + } else { > + done = tu->filter.nr_systemwide; > tu->filter.nr_systemwide++; > + } > write_unlock(&tu->filter.rwlock); > > - uprobe_apply(tu->inode, tu->offset, &tu->consumer, true); > + if (!done) > + uprobe_apply(tu->inode, tu->offset, &tu->consumer, true); > > return 0; > } > > static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event) > { > + bool done; > + > write_lock(&tu->filter.rwlock); > - if (event->hw.tp_target) > + if (event->hw.tp_target) { > list_del(&event->hw.tp_list); > - else > + done = tu->filter.nr_systemwide || > + (event->hw.tp_target->flags & PF_EXITING) || > + uprobe_filter_event(tu, event); > + } else { > tu->filter.nr_systemwide--; > + done = tu->filter.nr_systemwide; > + } > write_unlock(&tu->filter.rwlock); > > - uprobe_apply(tu->inode, tu->offset, &tu->consumer, false); > + if (!done) > + uprobe_apply(tu->inode, tu->offset, &tu->consumer, false); > > return 0; > } > -- > 1.5.5.1 >
-- Thanks and Regards Srikar Dronamraju
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