Return the correct value for sysconf(_SC_PAGESIZE)

Eric Blake eblake@redhat.com
Wed Nov 16 14:01:00 GMT 2016


On 11/16/2016 07:56 AM, Erik Bray wrote:

>> There is no good reason to use the non-POSIXy page size.  It doesn't
>> help you in the least for any pagesize-related functionality.  Mmap
>> as well as malloc and friends only work with _SC_PAGESIZE sized pages.
>>
>> It sounds as if you're looking for a solution for which there's no
>> problem...
> 
> 
> FWIW the background here is that I'm working on porting psutil [1] to
> Cygwin, and trying to accomplish as much as *possible* through the
> POSIX interfaces without having to fall back on the Windows API.  It's
> actually a great exercise in what is and isn't possible with Cygwin :)
> 
> In this case I was trying to compute process memory usage from
> /proc/<pid>/statm which gives values in page counts, so I need the
> page size (the actual page size) to compute the values in bytes.

If /proc/<pid>/statm is reporting memory in multiples that are not the
POSIX _SC_PAGESIZE, that is a bug in the statm file emulation that
should be fixed there.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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