Re: [PATCH v2 1/6] powerpc/perf: Define big-endian version of perf_mem_data_src

From: Madhavan Srinivasan
Date: Tue Mar 07 2017 - 07:45:31 EST



On Monday 06 March 2017 04:52 PM, Peter Zijlstra wrote:
On Mon, Mar 06, 2017 at 04:13:08PM +0530, Madhavan Srinivasan wrote:
From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>

perf_mem_data_src is an union that is initialized via the ->val field
and accessed via the bitmap fields. For this to work on big endian
platforms, we also need a big-endian represenation of perf_mem_data_src.
Doesn't this break interpreting the data on a different endian machine?

IIUC, we will need this patch to not to break the interpreting data
on a different endian machine. Data collected from power8 LE/BE
guests with this patchset applied. Kindly correct me if I missed
your question here.


With this patchset applied, perf.data from a power8 BigEndian guest:
==============================================================

$ sudo ./perf record -d -e mem_access ls
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.007 MB perf.data (8 samples) ]

$ sudo ./perf report --mem-mode --stdio
# To display the perf.data header info, please use --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 8 of event 'mem_access'
# Total weight : 8
# Sort order : local_weight,mem,sym,dso,symbol_daddr,dso_daddr,snoop,tlb,locked
#
# Overhead Local Weight Memory access Symbol Shared Object Data Symbol Data Object Snoop TLB access Locked
# ........ ............ ........................ ........................... ................ ...................................... .................................. ............ ...................... ......
#
25.00% 0 L2 hit [H] 0xc00000000000c910 [unknown] [H] 0xc000000f170e5310 [unknown] N/A N/A No
12.50% 0 L2 hit [k] .idle_cpu [kernel.vmlinux] [k] __per_cpu_offset+0x68 [kernel.vmlinux].data..read_mostly N/A N/A No
12.50% 0 L2 hit [H] 0xc00000000000ca58 [unknown] [H] 0xc000000f170e5200 [unknown] N/A N/A No
12.50% 0 L3 hit [k] .copypage_power7 [kernel.vmlinux] [k] 0xc00000002f6fc600 [kernel.vmlinux].bss N/A N/A No
12.50% 0 L3 hit [k] .copypage_power7 [kernel.vmlinux] [k] 0xc00000003f8b1980 [kernel.vmlinux].bss N/A N/A No
12.50% 0 Local RAM hit [k] ._raw_spin_lock_irqsave [kernel.vmlinux] [k] 0xc000000033b5bdf4 [kernel.vmlinux].bss Miss N/A No
12.50% 0 Remote Cache (1 hop) hit [k] .perf_iterate_ctx [kernel.vmlinux] [k] 0xc000000000e88648 [kernel.vmlinux] HitM N/A No


perf report from power8 LittleEndian guest (with this patch applied to perf tool):
==================================================================================

$ ./perf report --mem-mode --stdio -i perf.data.p8be.withpatch
No kallsyms or vmlinux with build-id ca8a1a9d4b62b2a67ee01050afb1dfa03565a655 was found
/boot/vmlinux with build id ca8a1a9d4b62b2a67ee01050afb1dfa03565a655 not found, continuing without symbols
No kallsyms or vmlinux with build-id ca8a1a9d4b62b2a67ee01050afb1dfa03565a655 was found
/boot/vmlinux with build id ca8a1a9d4b62b2a67ee01050afb1dfa03565a655 not found, continuing without symbols
# To display the perf.data header info, please use --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 8 of event 'mem_access'
# Total weight : 8
# Sort order : local_weight,mem,sym,dso,symbol_daddr,dso_daddr,snoop,tlb,locked
#
# Overhead Local Weight Memory access Symbol Shared Object Data Symbol Data Object Snoop TLB access Locked
# ........ ............ ........................ ...................... ................ ...................... ................ ............ ...................... ......
#
25.00% 0 L2 hit [H] 0xc00000000000c910 [unknown] [H] 0xc000000f170e5310 [unknown] N/A N/A No
12.50% 0 L2 hit [k] 0xc0000000000f4d0c [kernel.vmlinux] [k] 0xc000000000f2dac8 [kernel.vmlinux] N/A N/A No
12.50% 0 L2 hit [H] 0xc00000000000ca58 [unknown] [H] 0xc000000f170e5200 [unknown] N/A N/A No
12.50% 0 L3 hit [k] 0xc00000000006b560 [kernel.vmlinux] [k] 0xc00000002f6fc600 [kernel.vmlinux] N/A N/A No
12.50% 0 L3 hit [k] 0xc00000000006b560 [kernel.vmlinux] [k] 0xc00000003f8b1980 [kernel.vmlinux] N/A N/A No
12.50% 0 Local RAM hit [k] 0xc00000000094ad14 [kernel.vmlinux] [k] 0xc000000033b5bdf4 [kernel.vmlinux] Miss N/A No
12.50% 0 Remote Cache (1 hop) hit [k] 0xc0000000001ce31c [kernel.vmlinux] [k] 0xc000000000e88648 [kernel.vmlinux] HitM N/A No



With this patch, perf.data from a power8 LE guest:
===================================================

$ sudo ./perf record -d -e mem_access ls
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.010 MB perf.data (6 samples) ]

$ sudo ./perf report --mem-mode --stdio
# To display the perf.data header info, please use --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 6 of event 'mem_access'
# Total weight : 6
# Sort order : local_weight,mem,sym,dso,symbol_daddr,dso_daddr,snoop,tlb,locked
#
# Overhead Local Weight Memory access Symbol Shared Object Data Symbol Data Object Snoop TLB access Locked
# ........ ............ ........................ ...................... ................ ...................... ................ ............ ...................... ......
#
16.67% 0 L2 hit [.] _init ls [.] 0x000001002ef4dd71 [heap] N/A N/A No
16.67% 0 L2 hit [k] irq_exit [kernel.vmlinux] [k] 0xc0000000ff6e2080 [kernel.vmlinux] N/A N/A No
16.67% 0 L2 hit [H] 0xc0000000000ba210 [unknown] [H] 0xc00000075ce2fe38 [unknown] N/A N/A No
16.67% 0 L2 hit [H] 0xc00000000000bdb0 [unknown] [H] 0xc00000075ce2fee0 [unknown] N/A N/A No
16.67% 0 L2 hit [H] 0xc0000000000bb444 [unknown] [H] 0xc00000075ce30490 [unknown] N/A N/A No
16.67% 0 L3 hit [H] 0x0000000000066524 [unknown] [H] 0xc0000000014e0000 [unknown] N/A N/A No

perf report from power7 BE guest(with this patch applied to perf tool):
=========================================================================

$ ./perf report --mem-mode --stdio
No kallsyms or vmlinux with build-id 06240a7589956e7d388bdffdab9f7f138834fa81 was found
/lib/modules/4.10.0-rc5+/build/vmlinux with build id 06240a7589956e7d388bdffdab9f7f138834fa81 not found, continuing without symbols
No kallsyms or vmlinux with build-id 06240a7589956e7d388bdffdab9f7f138834fa81 was found
/lib/modules/4.10.0-rc5+/build/vmlinux with build id 06240a7589956e7d388bdffdab9f7f138834fa81 not found, continuing without symbols
/usr/bin/ls with build id cf69c39cf0d28e5be86c03de5c556e3ce8d6ce27 not found, continuing without symbols
# To display the perf.data header info, please use --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 6 of event 'mem_access'
# Total weight : 6
# Sort order : local_weight,mem,sym,dso,symbol_daddr,dso_daddr,snoop,tlb,locked
#
# Overhead Local Weight Memory access Symbol Shared Object Data Symbol Data Object Snoop TLB access Locked
# ........ ............ ........................ ...................... ................ ...................... ................ ............ ...................... ......
#
16.67% 0 L2 hit [k] 0xc0000000000d3cc8 [kernel.vmlinux] [k] 0xc0000000ff6e2080 [kernel.vmlinux] N/A N/A No
16.67% 0 L2 hit [.] 0x0000000000012ba8 ls [.] 0x000001002ef4dd71 [heap] N/A N/A No
16.67% 0 L2 hit [H] 0xc0000000000ba210 [unknown] [H] 0xc00000075ce2fe38 [unknown] N/A N/A No
16.67% 0 L2 hit [H] 0xc00000000000bdb0 [unknown] [H] 0xc00000075ce2fee0 [unknown] N/A N/A No
16.67% 0 L2 hit [H] 0xc0000000000bb444 [unknown] [H] 0xc00000075ce30490 [unknown] N/A N/A No
16.67% 0 L3 hit [H] 0x0000000000066524 [unknown] [H] 0xc0000000014e0000 [unknown] N/A N/A No


Maddy