Re: [PATCH 00/16] Remove hash page table slot tracking from linux PTE

Paul Mackerras [off-list ref] writes:

On Fri, Oct 27, 2017 at 10:57:13AM +0530, Aneesh Kumar K.V wrote:

quoted

On 10/27/2017 10:04 AM, Paul Mackerras wrote:

quoted

How do we interpret these numbers?  Are they times, or speed?  Is
larger better or worse?

Sorry for not including the details. They are time in seconds. Test case is
a modified mmap_bench included in powerpc/selftest.

quoted

Can you give us the mean and standard deviation for each set of 5
please?

powernv without patch
median= 51.432255
stdev = 0.370835

with patch
median = 50.739922
stdev = 0.06419662

pseries without patch
median = 116.617884
stdev = 3.04531023

with patch no hcall
median = 119.42494
stdev = 0.85874552

with patch and hcall
median = 117.735808
stdev = 2.7624151

So on powernv, the patch set *improves* performance by about 1.3%
(almost 2 standard deviations).  Do we know why that is?

I looked at the perf data and with the test, we are doing larger number
of hash faults and then around 10k flush_hash_range. Can the small
improvement in number be due to the fact that we are not storing slot
number when doing an insert now?. Also in the flush path we are now not
using real_pte_t.

aneesh