On 11/8/18 12:14 PM, Grygorii Strashko wrote: > > > On 11/8/18 6:00 AM, Sebastian Andrzej Siewior wrote: >> 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 :) > > Ops 8-). at least subj is correct. > >> >>> 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? > > Yes (in general) - it's collected with systemd, so some daemons are active. > >> The Kconfig help says "faster TLB lookup". Interesting. >> Are the 16k pages in between (latency wise) by any chance? > > I'll try it. no i'll not, at least not fast. with 16k pages enabled I can't boot TI 4.14 kernel - 4.14.71-rt44. No msg in log, just "Starting kernel ..." -- regards, -grygorii
