On 4/13/20 2:33 PM, Mike Kravetz wrote: > On 4/10/20 8:47 AM, Nitesh Narayan Lal wrote: >> Hi Mike, >> >> On platforms that support multiple huge page sizes when 'hugepagesz' is not >> specified before 'hugepages=', hugepages are not allocated. (For example >> if we are requesting 1GB hugepages) > Hi Nitesh, > > This should only be an issue with gigantic huge pages. This is because > hugepages=X not following a hugepagesz=Y specifies the number of huge pages > of default size to allocate. It does not currently work for gigantic pages. I see, since we changed the default hugepages to gigantic pages and we missed 'hugepagesz=' no page were allocated of any type. > In the other thread, I provided this explanation as to why: > It comes about because we do not definitively set the default huge page size > until after command line processing (in hugetlb_init). And, we must > preallocate gigantic huge pages during command line processing because that > is when the bootmem allocater is available. > > I will be looking into modifying this behavior to allocate the pages as > expected, even for gigantic pages. Nice, looking forward to it. > >> In terms of reporting meminfo and /sys/kernel/../nr_hugepages reports the >> expected results but if we use sysctl vm.nr_hugepages then it reports a non-zero >> value as it reads the max_huge_pages from the default hstate instead of >> nr_huge_pages. >> AFAIK nr_huge_pages is the one that indicates the number of huge pages that are >> successfully allocated. >> >> Does vm.nr_hugepages is expected to report the maximum number of hugepages? If >> so, will it not make sense to rename the procname? >> >> However, if we expect nr_hugepages to report the number of successfully >> allocated hugepages then we should use nr_huge_pages in >> hugetlb_sysctl_handler_common(). > This looks like a bug. Neither sysctl or the /proc file should be reporting > a non-zero value if huge pages do not exist. Yeap, as I mentioned it reports max_huge_pages instead of the nr_huge_pages. -- Thanks Nitesh
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