On Wed, Jan 07, 2015 at 07:24:52PM +0200, Kirill A. Shutemov wrote: > And how it's not an ABI break? I don't think this is an ABI break because the current behaviour is not changed unless you write "5" to /proc/pid/clear_refs. If you do, you are explicitly requesting the new functionality.
> We have never-lowering VmHWM for 9+ years. How can you know that nobody > expects this behaviour? This is why we sent an RFC [1] several weeks ago. We expect this to be used mainly by performance-related tools (e.g. profilers) and from the comments in the code [2] VmHWM seems to be a best-effort counter. If this is strictly a no-go, I can only think of the following two alternatives: 1. Add an extra resettable field to /proc/pid/status (e.g. resettable_hiwater_rss). While this doesn't violate the current definition of VmHWM, it adds an extra line to /proc/pid/status, which I think is a much bigger issue. 2. Introduce a new proc fs file to task_mmu (e.g. /proc/pid/profiler_stats), but this feels like overengineering. > And why do you reset hiwater_rss, but not hiwater_vm? This is a good point. Should we reset both using the same flag, or introduce a new one ("6")? [1] lkml.iu.edu/hypermail/linux/kernel/1412.1/01877.html [2] task_mmu.c:32: "... such snapshots can always be inconsistent." Petr -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/