Re: [PATCH] fs/select: add vmalloc fallback for select(2)

From	Vlastimil Babka <vbabka@suse.cz>
Newsgroups	linux.kernel
Subject	Re: [PATCH] fs/select: add vmalloc fallback for select(2)
Date	2016-09-27 14:00 +0200
Message-ID	<slZdg-D0-29@gated-at.bofh.it> (permalink)
References	(3 earlier) <skBPI-6j6-33@gated-at.bofh.it> <slWfn-7h7-9@gated-at.bofh.it> <slYKd-tC-11@gated-at.bofh.it> <slZ3z-zK-9@gated-at.bofh.it> <slZ3z-zK-15@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 09/27/2016 01:42 PM, Nicholas Piggin wrote:
> On Tue, 27 Sep 2016 11:37:24 +0000
> David Laight <David.Laight@ACULAB.COM> wrote:
>
>> From: Nicholas Piggin
>> > Sent: 27 September 2016 12:25
>> > On Tue, 27 Sep 2016 10:44:04 +0200
>> > Vlastimil Babka <vbabka@suse.cz> wrote:
>> >
>> >
>> > What's your customer doing with those selects? If they care at all about
>> > performance, I doubt they want select to attempt order-4 allocations, fail,
>> > then use vmalloc :)
>>
>> If they care about performance they shouldn't be passing select() lists that
>> are anywhere near that large.
>> If the number of actual fd is small - use poll().
>
> Right. Presumably it's some old app they're still using, no?

Process name suggests it's part of db2 database. It seems it has to implement 
its own interface to select() syscall, because glibc itself seems to have a 
FD_SETSIZE limit of 1024, which is probably why this wasn't an issue for all the 
years...

Thread

Re: [PATCH] fs/select: add vmalloc fallback for select(2) Jason Baron <jbaron@akamai.com> - 2016-09-23 18:50 +0200
  Re: [PATCH] fs/select: add vmalloc fallback for select(2) Vlastimil Babka <vbabka@suse.cz> - 2016-09-27 10:50 +0200
    Re: [PATCH] fs/select: add vmalloc fallback for select(2) Nicholas Piggin <npiggin@gmail.com> - 2016-09-27 13:30 +0200
      RE: [PATCH] fs/select: add vmalloc fallback for select(2) David Laight <David.Laight@ACULAB.COM> - 2016-09-27 13:50 +0200
        Re: [PATCH] fs/select: add vmalloc fallback for select(2) Nicholas Piggin <npiggin@gmail.com> - 2016-09-27 13:50 +0200
          Re: [PATCH] fs/select: add vmalloc fallback for select(2) Vlastimil Babka <vbabka@suse.cz> - 2016-09-27 14:00 +0200
            RE: [PATCH] fs/select: add vmalloc fallback for select(2) David Laight <David.Laight@ACULAB.COM> - 2016-09-28 18:40 +0200
              Re: [PATCH] fs/select: add vmalloc fallback for select(2) Vlastimil Babka <vbabka@suse.cz> - 2016-09-28 22:10 +0200

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