Re: low-level profiling

I'm not passing any flags related to code generation, I don't think. $HC -H64m -O -Rghc-timing -package array -H32m -hisuf hi -O1 -rtsopts -c Main.hs -o Main.o So that'd just be the native code generator, right?. $ uname -a Linux cam-05-unx 3.2.0-35-generic #55-Ubuntu SMP Wed Dec 5 17:42:16 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux Is there a objdump-ish way to directly look for these .size directives? Thanks Johan. On Fri, Feb 15, 2013 at 6:18 PM, Johan Tibell wrote:

On Fri, Feb 15, 2013 at 10:05 AM, Nicolas Frisby

...

wrote:

...

I'm way below my depth here, but I'd like to use the perf tool to see where a program is spending its time.

Unfortunately, the recipe here

http://hackage.haskell.org/trac/ghc/wiki/Debugging/LowLevelProfiling/Perf

isn't working for me. I get output like this instead

90.20% drbg_test drbg_test [.] 0x2515ef 5.71% drbg_test [kernel.kallsyms] [k] 0xffffffff8103e0ca 1.53% drbg_test libc-2.15.so [.] bsearch 1.02% drbg_test libc-2.15.so [.] 0x9194c 0.43% drbg_test libgmp.so.10.0.2 [.] __gmpz_mul_2exp 0.27% drbg_test libgmp.so.10.0.2 [.] __gmpz_add 0.16% drbg_test [vdso] [.] 0x7fffd3d25983 0.16% drbg_test libgmp.so.10.0.2 [.] __gmpn_lshift 0.10% drbg_test libgmp.so.10.0.2 [.] 0x13565 0.05% drbg_test libgmp.so.10.0.2 [.] __gmpz_init 0.05% drbg_test libc-2.15.so [.] __select 0.05% drbg_test libgmp.so.10.0.2 [.] __gmpn_modexact_1_odd 0.05% drbg_test libgmp.so.10.0.2 [.] __gmpz_realloc 0.05% drbg_test libc-2.15.so [.] __errno_location 0.05% drbg_test drbg_test [.] __gmpz_init@plt 0.05% drbg_test librt-2.15.so [.] clock_gettime 0.05% drbg_test libgmp.so.10.0.2 [.] __gmpn_add_n

Again --- below my depth here --- but I don't know how to investigate what 0x2515ef indicates. Does anyone have any pointers?

I was hoping that the address would be a nice RTS-ish symbol, like in the Wiki's examples.

I thought I fixed this issue (at least in the native backend). What was missing before was .size assembler directives that would let tools like perf know where a function started and ended. See this commit https://github.com/ghc/ghc/commit/32f24ddfd9549010dd345733c6f46f67196cacf6

Perhaps it broke at some point? Are you using the x86 backend?