Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1390641

Re: [patch 2/7] lib/hashmod: Add modulo based hash mechanism

Show all headers | View raw

On Thu, 28 Apr 2016, Linus Torvalds wrote:
> 
> I'd really hate to add *another* ad-hoc hash when the previous ad-hoc
> hash has been shown to be bad.

I completely agree.

I'm not a hashing wizard and I completely failed to understand why
hash_long/ptr are so horrible for the various test cases I ran.

So my ad hoc test was to use the only hash function I truly understand. It was
state of the art in my university days :) And surprise, surprise it worked
really well.

My main focus was really to solve this futex issue which plages various people
and not to dive into hashing theory for a few weeks.

I'll try to dig up some time to analyze the hash_long failure unless someone
familiar with the problem is beating me to it.

Thanks,

	tglx

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[patch 0/7] futex: Add support for process private hashing Thomas Gleixner <tglx@linutronix.de> - 2016-04-28 18:50 +0200
  [patch 1/7] futex: Add some more function commentry Thomas Gleixner <tglx@linutronix.de> - 2016-04-28 18:50 +0200
  [patch 2/7] lib/hashmod: Add modulo based hash mechanism Thomas Gleixner <tglx@linutronix.de> - 2016-04-28 18:50 +0200
    Re: [patch 2/7] lib/hashmod: Add modulo based hash mechanism Linus Torvalds <torvalds@linux-foundation.org> - 2016-04-28 20:40 +0200
      Re: [patch 2/7] lib/hashmod: Add modulo based hash mechanism Thomas Gleixner <tglx@linutronix.de> - 2016-04-29 01:30 +0200
        Re: [patch 2/7] lib/hashmod: Add modulo based hash mechanism Linus Torvalds <torvalds@linux-foundation.org> - 2016-04-29 04:30 +0200
          Re: [patch 2/7] lib/hashmod: Add modulo based hash mechanism Thomas Gleixner <tglx@linutronix.de> - 2016-04-30 15:10 +0200
            Re: [patch 2/7] lib/hashmod: Add modulo based hash mechanism Eric Dumazet <eric.dumazet@gmail.com> - 2016-04-30 18:50 +0200
              Re: [patch 2/7] lib/hashmod: Add modulo based hash mechanism Linus Torvalds <torvalds@linux-foundation.org> - 2016-04-30 19:20 +0200
                Re: [patch 2/7] lib/hashmod: Add modulo based hash mechanism Eric Dumazet <eric.dumazet@gmail.com> - 2016-04-30 19:40 +0200
      Re: [patch 2/7] lib/hashmod: Add modulo based hash mechanism Linus Torvalds <torvalds@linux-foundation.org> - 2016-04-29 23:20 +0200
        Re: [patch 2/7] lib/hashmod: Add modulo based hash mechanism Linus Torvalds <torvalds@linux-foundation.org> - 2016-04-30 02:00 +0200
          Re: [patch 2/7] lib/hashmod: Add modulo based hash mechanism Rik van Riel <riel@redhat.com> - 2016-04-30 03:40 +0200
          Re: [patch 2/7] lib/hashmod: Add modulo based hash mechanism Torvald Riegel <triegel@redhat.com> - 2016-05-02 11:40 +0200
        Re: [patch 2/7] lib/hashmod: Add modulo based hash mechanism Thomas Gleixner <tglx@linutronix.de> - 2016-04-30 17:30 +0200
  [patch 6/7] perf/bench/futex-hash: Support NUMA Thomas Gleixner <tglx@linutronix.de> - 2016-04-28 18:50 +0200
  [patch 3/7] futex: Hash private futexes per process Thomas Gleixner <tglx@linutronix.de> - 2016-04-28 18:50 +0200
  [patch 7/7] perf/bench/futex-hash: Support preallocate hash table Thomas Gleixner <tglx@linutronix.de> - 2016-04-28 18:50 +0200
  [patch 5/7] futex: Add sysctl knobs for process private hash Thomas Gleixner <tglx@linutronix.de> - 2016-04-28 18:50 +0200
  [patch 4/7] futex: Add op for hash preallocation Thomas Gleixner <tglx@linutronix.de> - 2016-04-28 18:50 +0200

csiph-web