* Andrea Arcangeli <aarcange@xxxxxxxxxx> wrote:
> So this takes more than 2 seconds away from 24 seconds reproducibly, and it
> means gcc now runs 8% faster. [...]
That's fantastic if systematic ... i'd give a limb for faster kbuild times in
the >2% range.
Would be nice to see a precise before/after 'perf stat' comparison:
perf stat -e cycles -e instructions -e dtlb-loads -e dtlb-load-misses --repeat 3 ...
that way we can see that the instruction count is roughly the same
before/after, the cycle count goes down and we can also see the reduction in
dTLB misses (and other advantages, if any).
Plus, here's a hugetlb usability feature request if you dont mind me
suggesting it.
This current usage (as root):
echo never > /sys/kernel/mm/transparent_hugepage/enabled
is fine for testing but it would be also nice to give finegrained per workload
tunability to such details. It would be _very_ nice to have app-inheritable
hugetlb attributes plus have a 'hugetlb' tool in tools/hugetlb/, which would
allow the per workload tuning of hugetlb uses. For example:
hugetlb ctl --never ./my-workload.sh
would disable hugetlb usage in my-workload.sh (and all sub-processes).
Running:
hugetlb ctl --always ./my-workload.sh
would enable it. [or something like that - maybe there are better naming schemes]
Other commands:
hugetlb stat
would show current allocation stats, etc.
Currently you have the 'hugetlbctl' app but IMO it limits the useful command
space to 'control' ops only - it would be _much_ better to use the Git model:
to name the tool in a much more generic way ('hugetlb' - the project name),
and then let sub-commands be added like Git (and perf ;-) does.
Git has more than 70 subcommands currently, trend growing. That command model
scales and works well for smaller projects like perf (or hugetlb) as well.
Anyway, was just a suggestion.
Ingo
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