Re: [RFC PATCH] mm: fadvise: avoid fadvise for fs without backing device

From	Shakeel Butt <shakeelb@google.com>
Newsgroups	linux.kernel
Subject	Re: [RFC PATCH] mm: fadvise: avoid fadvise for fs without backing device
Date	2017-08-23 02:30 +0200
Message-ID	<uhrIt-1Ej-1@gated-at.bofh.it> (permalink)
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>> It doesn't sound like a risky change to me, although perhaps someone is
>> depending on the current behaviour for obscure reasons, who knows.
>>
>> What are the reasons for this change?  Is the current behaviour causing
>> some sort of problem for someone?
>
> Yes, one of our generic library does fadvise(FADV_DONTNEED). Recently
> we observed high latency in fadvise() and notice that the users have
> started using tmpfs files and the latency was due to expensive remote
> LRU cache draining. For normal tmpfs files (have data written on
> them), fadvise(FADV_DONTNEED) will always trigger the un-needed remote
> cache draining.
>

Hi Andrew, do you have more comments or concerns?

>>
>>

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Re: [RFC PATCH] mm: fadvise: avoid fadvise for fs without backing device Shakeel Butt <shakeelb@google.com> - 2017-08-18 03:30 +0200
  Re: [RFC PATCH] mm: fadvise: avoid fadvise for fs without backing  device Andrew Morton <akpm@linux-foundation.org> - 2017-08-18 23:40 +0200
    Re: [RFC PATCH] mm: fadvise: avoid fadvise for fs without backing device Shakeel Butt <shakeelb@google.com> - 2017-08-19 01:20 +0200
      Re: [RFC PATCH] mm: fadvise: avoid fadvise for fs without backing device Shakeel Butt <shakeelb@google.com> - 2017-08-23 02:30 +0200

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