anolis: add a misc device driver cmn700_cache_scan to mitigate an ARM CMN erratum · Pull Request !5427 · anolis/cloud-kernel

1. anolis: ccs: add CPU utilization control functionality
2. anolis: ccs: flush repeated problematic addresses with higher frequency
3. anolis: ccs: add misc device driver cmn700_cache_scan

bugzilla: https://bugzilla.openanolis.cn/show_bug.cgi?id=20511

anolis: add a misc device driver cmn700_cache_scan to mitigate an ARM CMN erratum

For ARM CMN-700 r0-r2, if

- multiple CMN-700 instances are used (e.g. multi-dies chip) AND
- LLC SF (Snoop Filter) for a cache line in shared MESI state AND
- the LLC cache line is victimized

then, any further memory reading from the cache line address will not
fill the LLC cache but always go to DDR until the cache line is
evicted or invalidated from LLC SF.

The details of the erratum can be found at,
https://developer.arm.com/documentation/SDEN-2039384/1900/

To mitigate the erratum, a new SMC is implemented in ATF to
identify the affected cache lines via dumping the tags of the
cache lines in LLC SF and LLC.  A new misc device driver is
implemented in Linux kernel to call SMC to get the affected
cache lines and flush them to exit the problematic state when
requested by the user space via the misc device file writing.

The performance of many workloads are influenced by the erratum.
For example, after applying the fix, the MySQL OLTP query per
second can improve up to 18.4%.

We have finished functionality, fuzzy, stability, performance
test for the patchset.

All commands and parameters of the misc device file have been
tested with preset and random values.  The erratum mitigation
functionality is tested at the same time of LTP, stress-ng,
kvm-unit-test, etc. test suite to verify the stability of
system isn't compromised.

类型	指派人员	状态
审查	xunlei Guixin Liu	已完成 (0/0人)
测试	小龙已测试通过	已完成 (1/1人)

GVPanolis/cloud-kernel

搜索帮助

GVP anolis/cloud-kernel