| From 5c9e0d0fc9188bab0ae09c9c33df01938b0c1b6c Mon Sep 17 00:00:00 2001 |
| From: Khem Raj <raj.khem@gmail.com> |
| Date: Thu, 14 Apr 2022 09:25:33 -0700 |
| Subject: [PATCH] server: Adjust the cache alignment assumptions |
| |
| aarch64 has 256 for hardware_destructive_interference_size and gcc 12 |
| has added a warning to complain about mismatches which results in |
| static_assert failures |
| |
| In file included from src/mongo/s/commands/cluster_find_cmd.cpp:39: |
| src/mongo/db/stats/counters.h:185:47: error: static assertion failed: cache line spill |
| 185 | static_assert(sizeof(decltype(_together)) <= stdx::hardware_constructive_interference_size, |
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| The structure need to ensure true sharing for both the elements |
| so align it to hardware_constructive_interference_size instead |
| |
| Upstream-Status: Inappropriate [https://jira.mongodb.org/browse/SERVER-65664] |
| |
| Signed-off-by: Khem Raj <raj.khem@gmail.com> |
| --- |
| src/mongo/db/stats/counters.h | 6 +++--- |
| 1 file changed, 3 insertions(+), 3 deletions(-) |
| |
| --- a/src/mongo/db/stats/counters.h |
| +++ b/src/mongo/db/stats/counters.h |
| @@ -182,8 +182,8 @@ private: |
| AtomicWord<long long> requests{0}; |
| }; |
| CacheAligned<Together> _together{}; |
| - static_assert(sizeof(decltype(_together)) <= stdx::hardware_constructive_interference_size, |
| - "cache line spill"); |
| + static_assert(sizeof(Together) <= stdx::hardware_constructive_interference_size, |
| + "cache line spill"); |
| |
| CacheAligned<AtomicWord<long long>> _logicalBytesOut{0}; |
| |