diff options
author | Cliff Wickman <cpw@sgi.com> | 2005-10-27 10:29:08 -0500 |
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committer | Tony Luck <tony.luck@intel.com> | 2005-10-27 16:15:03 -0700 |
commit | 4ac0068f44f192f2de95a7bb36df3e19767a45fb (patch) | |
tree | 7971afe201d63657fceeb5770eb8247711ce69aa /arch/ia64/kernel/uncached.c | |
parent | 72ab373a5688a78cbdaf3bf96012e597d5399bb7 (diff) |
[IA64] ptrace - find memory sharers on children list
In arch/ia64/kernel/ptrace.c there is a test for a peek or poke of a
register image (in register backing storage).
The test can be unnecessarily long (and occurs while holding the tasklist_lock).
Especially long on a large system with thousands of active tasks.
The ptrace caller (presumably a debugger) specifies the pid of
its target and an address to peek or poke. But the debugger could be
attached to several tasks.
The idea of find_thread_for_addr() is to find whether the target address
is in the RBS for any of those tasks.
Currently it searches the thread-list of the target pid. If that search
does not find a match, and the shared mm-struct's user count indicates
that there are other tasks sharing this address space (a rare occurrence),
a search is made of all the tasks in the system.
Another approach can drastically shorten this procedure.
It depends upon the fact that in order to peek or poke from/to any task,
the debugger must first attach to that task. And when it does, the
attached task is made a child of the debugger (is chained to its children list).
Therefore we can search just the debugger's children list.
Signed-off-by: Cliff Wickman <cpw@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Diffstat (limited to 'arch/ia64/kernel/uncached.c')
0 files changed, 0 insertions, 0 deletions