Re: [patch 00/14] remap_file_pages protection support

[Ulrich Drepper <drepper@redhat.com>]

Blaisorblade wrote:
>> I've not seen much of this if any at all, the various caches that are in
>> place for these lookups seem to function quite well; what we did see was
>> glibc's malloc implementation being mistuned resulting in far too many
>> mmaps than needed (which in turn leads to far too much page zeroing
>> which is the really expensive part. It's not the vma lookup that is
>> expensive, it's the page zeroing)
> Even to this email, I hope Ulrich will answer.

All I can say is that some of our guys tuning a big application on a
customer's site reported seeing the VMA lookups being on the profile
list.  This was some huge Java program.  It might be that every other
page had a different protection, executable or not, read-only mmap etc.
 And data access for very non-local.

I cannot say more since this was near to the end of the trials.

-- 
➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖

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