Messages in this thread | | | Date | Sat, 6 Jun 2015 21:41:10 +0430 | Subject | Re: Using perf on AMD 15h | From | Mahmood Naderan <> |
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Bringing up my question one more time since it may be lost in the high volume of messages.
Hope to receive an idea...
On 6/6/15, Mahmood Naderan <mahmood.nt@gmail.com> wrote: > Hi Guys, > My first question is, does the version of kernel affects the perf > functionality? I mean fixing bugs and ... > Currently, the kernel version is 2.6.39 and here is the problem: > > According tot he BKDG of AMD 15h, it is possbile to disable the > hardware prefetcher by setting some bits of MSRC001_1022 > > 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. > > > > So in order to disable all prefetch configs, I have to write 0xA008 to > that MSR. I did that for all cores using > > [root@tiger exe]# wrmsr -a 0xc0011022 0xA008 > [root@tiger exe]# rdmsr -a -x -0 0xc0011022 > 000000000000a008 > ... > > > However, when I run perf along with the command, the prefetch ststs > are non-zero! > > > [root@tiger exe]# perf stat -e > L1-dcache-loads:uk,L1-dcache-prefetches:uk,L1-dcache-prefetch-misses:uk > ./bzip2_base.amd64-m64-gcc44-nn > spec_init > Tested 64MB buffer: OK! > Performance counter stats for './bzip2_base.amd64-m64-gcc44-nn': > 55,341,597,193 L1-dcache-loads:uk > 1,047,662,614 L1-dcache-prefetches:uk > 0 L1-dcache-prefetch-misses:uk > 35.921618464 seconds time elapsed > > > > > I expect to see 0 in front of L1-dcache-prefetches. Don't you? > I have stuck at this problem. I appreciate any feedback and comment. > > > Regards, > Mahmood >
-- Regards, Mahmood
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