Bug 28355 - 在支持向量指令的机器上进行fio测试性能出现劣化
Summary: 在支持向量指令的机器上进行fio测试性能出现劣化
Status: NEW
Alias: None
Product: ANCK 6.6 Dev
Classification: ANCK
Component: ARCH(unspecified) (show other bugs) ARCH(unspecified)
Version: 6.6.y-3
Hardware: All Linux
: P3-Medium S3-normal
Target Milestone: ---
Assignee: zhangjing
QA Contact: shuming
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2025-12-22 17:04 UTC by gaorui
Modified: 2025-12-23 10:53 UTC (History)
3 users (show)

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Description gaorui 2025-12-22 17:04:57 UTC 
Description of problem:
在支持向量指令的机器上进行fio测试性能出现劣化
4K随机读（IOPS）4K随机写（IOPS）4K随机读（BW）4K随机写（BW）4K随机读（Lat）4K随机写（Lat）
向量指令   507k 470k 2077MB/s 1925MB/s 62.95us 67.93us
非向量指令 535k 481k 2192MB/s 1968MB/s 59.63us 66.43us

从结果上看，修改为降级拷贝后，性能会有提升， RV-kernel 的 热点在fallback_scalar_usercopy向量拷贝性能差

Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1. 修改kernel的V_UCOPY_THRESHOLD门限，使所有的用户态拷贝走降级拷贝（标量）修改向量拷贝门限值为99999
2.使用fio测试4k随机读写


Actual results:


Expected results:


Additional info:
Comment 1 小龙 admin 2025-12-23 10:53:25 UTC 
The PR Link: https://gitee.com/anolis/cloud-kernel/pulls/6248