Re: [PATCH 00/14] Present useful limits to user (v2)

H. Peter Anvin
2016-07-15T20:54:44Z

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On July 15, 2016 6:59:56 AM PDT, Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org> wrote:
>On Fri, Jul 15, 2016 at 01:52:48PM +0000, Topi Miettinen wrote:
>> On 07/15/16 12:43, Peter Zijlstra wrote:
>> > On Fri, Jul 15, 2016 at 01:35:47PM +0300, Topi Miettinen wrote:
>> >> Hello,
>> >>
>> >> There are many basic ways to control processes, including
>capabilities,
>> >> cgroups and resource limits. However, there are far fewer ways to
>find out
>> >> useful values for the limits, except blind trial and error.
>> >>
>> >> This patch series attempts to fix that by giving at least a nice
>starting
>> >> point from the highwater mark values of the resources in question.
>> >> I looked where each limit is checked and added a call to update
>the mark
>> >> nearby.
>> >
>> > And how is that useful? Setting things to the high watermark is
>> > basically the same as not setting the limit at all.
>>
>> What else would you use, too small limits?
>
>That question doesn't make sense.
>
>What's the point of setting a limit if it ends up being the same as
>no-limit (aka unlimited).
>
>If you cannot explain; and you have not so far; what use these values
>are, why would we look at the patches.

One reason is to catch a malfunctioning process rather than dragging the whole system down with it. It could also be useful for development.
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