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SubjectRe: arm64 + ARM64_64K_PAGES=y
On 2018-11-06 15:34:55 [-0600], Grygorii Strashko wrote:
> Hi All,
Hi,

> Do anybody tried to use ARM64 RT with 76K pages enabled?

75 would be an off by one but this :)

> My attempt shows that enabling CONFIG_ARM64_64K_PAGES=y increases latencies by ~30%
>
> cyclictest -n -m -Sp98 -q -D2m with CONFIG_ARM64_64K_PAGES=y
>
>
> T: 0 ( 772) P:98 I:1000 C: 120000 Min: 7 Act: 13 Avg: 10 Max: 85
> T: 1 ( 773) P:98 I:1500 C: 79998 Min: 7 Act: 13 Avg: 10 Max: 71
> T: 2 ( 774) P:98 I:2000 C: 59997 Min: 7 Act: 11 Avg: 11 Max: 64
> T: 3 ( 775) P:98 I:2500 C: 47996 Min: 7 Act: 14 Avg: 12 Max: 66
>
>
> cyclictest -n -m -Sp98 -q -D2m with CONFIG_ARM64_64K_PAGES=n
>
>
> T: 0 ( 697) P:98 I:1000 C: 120000 Min: 7 Act: 10 Avg: 9 Max: 38
> T: 1 ( 698) P:98 I:1500 C: 79987 Min: 7 Act: 10 Avg: 10 Max: 32
> T: 2 ( 699) P:98 I:2000 C: 59981 Min: 7 Act: 14 Avg: 11 Max: 46
> T: 3 ( 700) P:98 I:2500 C: 47977 Min: 6 Act: 11 Avg: 10 Max: 45

So this is an idle system?
The Kconfig help says "faster TLB lookup". Interesting.
Are the 16k pages in between (latency wise) by any chance?

> --
> regards,
> -grygorii

Sebastian

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