RE: HUGETLB commit handling.

[Seth, Rohit]

Andy Whitcroft <> wrote on Thursday, April 08, 2004 9:36 AM:

> We have been looking at the HUGETLB page commit issue (offlist) and
> are close a final merged patch.  However, our testing seems to have
> thrown up an inconsistency in interface which we are not sure whether
> to fix or not.   
> 
> With normal shm segments we commit the pages we will need at shmget()
> time. 
> The real pages being allocated on demand.  With hugetlb pages we
> currently do not manage commit, but allocate them on map, shmat() in
> this case.  When we add commit handling it would seem most
> appropriate to commit the pages in shmget() as for small page
> mappings.  However, this might seem to change the semantics slightly,
> in that if there is insufficient hugepages available then the failure
> would come at shmget() and not shmat() time.      
> 
> I would contend this is the right thing to do, as it makes the
> semantics of hugepages match that of the existing small pages.  We
> are looking for a consensus as this might be construed as a semantic
> change.   
> 

IMO, doing this accounting check at shmget time seems reasonable as it
aligns the accouting semantics of normal and hugepages.


> Thoughts.
> 
> -apw
> 
> 
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