Messages in this thread | | | Date | Fri, 14 Mar 2014 07:13:00 -0700 | From | Andi Kleen <> | Subject | Re: [PATCH v1 03/11] perf: Allow for multiple ring buffers per event |
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> > The other big problem is scalability. Even if it was somehow possible > > to make this scheme work the IPIs for flushing would kill performance > > on any multi threaded client. Given perf is not multi-threaded today, but > > it doesn't seem a good idea to design the interface assuming no client ever > > will be. > > Well any mmap()ed interface that wants to swap buffers will have this > same problem.
There's no need to swap buffers in a sane design. The perf ring buffer or the ftrace buffer don't need this. There's no need for a PT buffer to do so either.
> > You can restrict the TLB flushing to the threads that poll() on the > relevant events. This just means other threads will see old/partial > data, but that shouldn't be a problem as they shouldn't be looking in > the first place.
Then we get incoherent processes. You're not serious about that are you?
-Andi
-- ak@linux.intel.com -- Speaking for myself only
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