Re: question: TLB sharing between child processes

From: Peter Chubb <>
Date: 2006-08-07 08:54:51
>>>>> "Sanjay" == Sanjay Bhandari <> writes:

Sanjay> (If this is the wrong forum for this question, a pointer to
Sanjay> the right one will be appreciated)
Sanjay> What can I expect in terms of TLB and cache sharing between
Sanjay> different processes when they are all non-exec'ed children of
Sanjay> the same parent (i.e. fork but no exec)?

There is no TLB sharing in standard Linux.  Matt Chapman had a patch
that enabled TLB sharing for memory regions with the same protections
and virtual address in different address spaces; benchmarking showed a
very large reduction in ITLB misses, but lesser reduction in DTLB
misses (COW means that data areas are not actually shared).  Overall,
ITLB misses weren't a big enough factor in the workloads we had
to make a real difference.  If you had a workload that had a large
shared memory region mapped into the same address in multiple
processes, the tradeoffs may differ.

Itanium caches are physically mapped, so they are always shared.

Dr Peter Chubb           ERTOS within National ICT Australia

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Received on Mon Aug 07 08:55:32 2006

This archive was generated by hypermail 2.1.8 : 2006-08-07 08:55:45 EST