Re: Enable/disable hardware prefetcher via Oprofile

Mahmood N <[email protected]>
Newsgroups gmane.linux.oprofile
Message-ID <[email protected]>
Well I want to set/reset 13th and 15th bit number which controls the hardware prefetcher according to the BKDG The value of 0x1000 equals 4096 which says the 13th bit is 1 and all others are zero. Here are some more examples

[root@tiger msr-tools-master]# ./wrmsr -p 0 0xc0011022 0x0
[root@tiger msr-tools-master]# ./rdmsr -p 0 -x -0 0xc0011022
0000000000000000
[root@tiger msr-tools-master]# ./wrmsr -p 0 0xc0011022 0xa
[root@tiger msr-tools-master]# ./rdmsr -p 0 -x -0 0xc0011022
000000000000000a
[root@tiger msr-tools-master]# ./wrmsr -p 0 0xc0011022 0xaa
[root@tiger msr-tools-master]# ./rdmsr -p 0 -x -0 0xc0011022
000000000000000a[root@tiger msr-tools-master]# ./wrmsr -p 0 0xc0011022 0x3
[root@tiger msr-tools-master]# ./rdmsr -p 0 -x -0 0xc0011022
0000000000000003
[root@tiger msr-tools-master]# ./wrmsr -p 0 0xc0011022 0x1000
[root@tiger msr-tools-master]# ./rdmsr -p 0 -x -0 0xc0011022
0000000000000000


The last one is what I want. However, it doesn't work correctly., Surprisingly, bits 3-0 are reserved but writing 3 which is 11 correctly works!




MSRC001_1022 Data Cache Configuration (DC_CFG)
Bits       ///////     Description
63:16    ///////  Reserved.
15    ///////  DisPfHwForSw. Read-write. Reset: 0. 1=Disable hardware prefetches for software prefetches.
14    ///////  Reserved.
13    ///////  DisHwPf. Read-write. Reset: 0. 1=Disable the DC hardware prefetcher. BIOS: See 2.3.3 [Using L2 Cache as General Storage During Boot].
12:10    ///////  Reserved.
9:5    ///////  Reserved.
4    ///////  DisSpecTlbRld. Read-write. Reset: 0. 1=Disable speculative TLB reloads. BIOS: See 2.3.3 [UsingL2 Cache as General Storage During Boot].
3:0    ///////  Reserved.


Regards,
Mahmood

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