Messages in this thread | | | Date | Fri, 23 Jan 2015 00:28:38 +0000 | Subject | Re: [PATCH v2 2/2] task_mmu: Add user-space support for resetting mm->hiwater_rss (peak RSS) | From | Primiano Tucci <> |
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On Thu, Jan 22, 2015 at 11:27 PM, David Rientjes <rientjes@google.com> wrote: > If you reset the hwm for a process, rss grows to 100MB, another process > resets the hwm, and you see a hwm of 2MB, that invalidates the hwm > entirely.
Not sure I follow this scenario. Where does the 2MB come from? How can you see a hwm of 2MB, under which conditions? HVM can never be < RSS. Again, what you are talking about is the case of two profilers racing for using the same interface (hwm). This is the same case today of the PG_referenced bit.
> The hwm is already defined as the > highest rss the process has attained, resetting it and trying to make any > inference from the result is racy and invalidates the actual value which > is useful. The counter arugment is: once you have one very high peak, the hvm becomes essentially useless for the rest of the lifetime of the process (until a higher peak comes). This makes very hard to understand what is going on in the meanwhile (from userspace).
Anyways, are you proposing to pursue a different approach? Is the approach 2. that petrcermark@ proposed in the beginning of the thread going to address this concern?
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