I don't know how you are measuring excessive with the alpha just posted there are no timing or memory diffs on linux for segsizes 64Ki 4Ki 8Ki 64Mi add usage to VMALLOC_OPTIONS to get a summary of total region usage in the last line all the segsizes show ~250Mi total usage
$ time VMALLOC_OPTIONS=segsize=64Ki $SHELL ./t01 real 0m14.61s user 0m14.45s sys 0m0.14s $ time VMALLOC_OPTIONS=segsize=4Mi $SHELL ./t01 real 0m14.51s user 0m14.36s sys 0m0.14s $ time VMALLOC_OPTIONS=segsize=8Mi $SHELL ./t01 real 0m14.68s user 0m14.48s sys 0m0.19s $ time VMALLOC_OPTIONS=segsize=64Mi $SHELL ./t01 real 0m14.49s user 0m14.33s sys 0m0.14s $ time VMALLOC_OPTIONS=segsize=64Mi,usage $SHELL ./t01 vmalloc: 0x25c2064e6000 67108864 init vmalloc: 0x25c2064e6000 67108864 init vmalloc: 0x25c2064e6000 67108864 region 0x007db200 size=268435456 segs=1 packs=1 busy=58% cache=115424/1801 real 0m15.03s user 0m14.61s sys 0m0.40s On Tue, Dec 10, 2013 at 4:16 AM, Lionel Cons <lionelcons1...@gmail.com>wrote: > On 6 December 2013 16:18, Glenn Fowler <glenn.s.fow...@gmail.com> wrote: > > On Thu, Dec 5, 2013 at 6:41 PM, Roland Mainz <roland.ma...@nrubsig.org> > > wrote: > >> 2. The default block size by the normal |mmap(MAP_ANON)| allocator is > >> 1MB. This is IMHO far to small because there is IMO not enough space > >> for the coalescing algorithm to operate and a *lot* of fragmentation > >> occurs. > >> IMHO a _minimum_ page size of 4MB should be picked (as a side-effect > >> the shell would get 4MB or 2MB largepages on platforms like Solaris > >> automagically). > > > > > > default block size upped to 4Mi and pagesize=<n>[KMGP][i] can ovveride in > > VMALLOC_OPTIONS for testing > > A default block size of 4Mi is not sufficient on linux/x86-64 and > Solaris/x86-64 to prevent the excessive memory consumption. I've > played with script to create a graph to see where the excesses stop > and the turning point is at 8.4Mi. > > So, if the default block size is bumped it should be bumped to at least > 8Mi. > > Lionel >
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