touch-packages team mailing list archive

[Daniel van Vugt <daniel.van.vugt@xxxxxxxxxxxxx>]

Public bug reported:

On the N4, Mir spends 12%+ CPU time in get_hooked_symbol (libhybris-
common). Actually callgrind can't decide; it's somewhere between 12% and
46000% ;)

So it's big. Looking at the hybris code, there's a rather large
bottleneck that's obvious: get_hooked_symbol does a linear search (many
times) of a large list of strings using strmp alone. That's why 22132
calls to get_hooked_symbol are yielding over 5 million calls to strcmp.

Upstream hybris appears to have been modified to use a cache/hashing
instead of the ugly linear search we have.

** Affects: mir
     Importance: Medium
     Assignee: Daniel van Vugt (vanvugt)
         Status: In Progress

** Affects: libhybris (Ubuntu)
     Importance: Undecided
     Assignee: Daniel van Vugt (vanvugt)
         Status: In Progress


** Tags: performance

** Also affects: libhybris (Ubuntu)
   Importance: Undecided
       Status: New

** Changed in: libhybris (Ubuntu)
     Assignee: (unassigned) => Daniel van Vugt (vanvugt)

** Changed in: libhybris (Ubuntu)
       Status: New => In Progress

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Touch seeded packages, which is subscribed to libhybris in Ubuntu.
https://bugs.launchpad.net/bugs/1343198

Title:
  Mir spends 12%+ CPU time in get_hooked_symbol (libhybris-common)

Status in Mir:
  In Progress
Status in “libhybris” package in Ubuntu:
  In Progress

Bug description:
  On the N4, Mir spends 12%+ CPU time in get_hooked_symbol (libhybris-
  common). Actually callgrind can't decide; it's somewhere between 12%
  and 46000% ;)

  So it's big. Looking at the hybris code, there's a rather large
  bottleneck that's obvious: get_hooked_symbol does a linear search
  (many times) of a large list of strings using strmp alone. That's why
  22132 calls to get_hooked_symbol are yielding over 5 million calls to
  strcmp.

  Upstream hybris appears to have been modified to use a cache/hashing
  instead of the ugly linear search we have.

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