Messages in this thread | | | Date | Sat, 19 Jul 2003 00:53:28 +0200 | From | Andrea Arcangeli <> | Subject | Re: 2.4.22pre6aa1 |
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On Fri, Jul 18, 2003 at 03:48:24PM -0700, William Lee Irwin III wrote: > On Sat, Jul 19, 2003 at 12:27:50AM +0200, Andrea Arcangeli wrote: > > bigpages= is a documented API that has to be used in production, so I > > can easily add the hugetlbfs API but I guess I've to keep this one > > anyways. I also would need to verify the performance of hugetlbfs before > > suggesting migrating to it, for example I don't want > > preallocation/prefaulting (IIRC hugetlbfs preallocates everything). I > > also like the single huge array of page pointers, that is very hardwired > > but optimal for those workloads. > > Most of the complaints I've gotten are about lack of support for mixed > PSE and non-PSE mappings, not preallocation or performance (generally > its usage doesn't involve creation/destruction cycle performance > requirements, and most of the time they intend to use 100% of the memory). > > It's basically too stupid and operating on too small a data set to > screw up performance-wise apart from creation/destruction, which is not > intended to be performant (and will never be; it blits oversized areas). > > I wouldn't mind hearing of what you believe is missing, so long as it's > within the constraints of what's mergeable. =(
I tend to think the creation/destruction will be the most noticeable performance difference in practice. allocating 42G in a single block will take a bit of time ;). I'm not necessairly worse or unacceptable, but it's different. And I feel I've to retain the bigpages= API (as an API not as in implementation) anyways. Furthmore I'm unsure if hugtlbfs is relaxed like the shm-largpeage patch is, I mean, it should be possible to mmap the stuff with 4k granularty too, or stuff could break due that change of API too.
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