On 01/16/18 09:34 AM, Luke Diamand wrote: > On 16 January 2018 at 03:33, Luke Diamand <l...@diamand.org> wrote: > > Hi! > > > > I could be wrong about this, but I'm finding a roughly 10x slowdown on > > ARM between 1.2.1 and current HEAD (e1ca8748). > > > > I have a small test program here: > > > > https://gist.github.com/luked99/7c67d94da5c33cac5a1b41a500013355
I think there is a similar perf test program under tests/, 'make perf' > > > > On my Raspberry Pi 2, this is getting ~180us to do a self-backtrace in > > 1.2.1 and around 1.8ms in HEAD. > > > > I tried running perf, and that seems to be saying that it is opening > > and closing files a lot. > > > > I also had a go at git bisecting, but there's a separate bug which was > > introduced and then fixed which caused it to segfault, which overlaps > > with this problem, along with some other performance regression fixes. > > > > 90d0d15c4ec3bb812dcb44c081757ebf6756cc6b didn't crash, but was slow. > > 2a5d1a629634b3225fccb1ed8a0a765bccc77f2e crashed. > > v1.2.1 is fast. > > > > I'm configuring with: > > > > CC=arm-linux-gnueabihf-gcc CFLAGS="-g" configure --disable-debug > > --host=arm-linux \ > > --enable-shared --disable-static --with-sysroot=/home/lgd/arm > > --enable-maintainer-mode \ > > --disable-debug-frame --disable-block-signals > > > > Any ideas as to what's going on? > > If do: > export UNW_ARM_UNWIND_METHOD=4 > > (so only use the exidx tables) then it drops from ~1ms to 95us. > > My image only has the exidx tables; it's built with gcc using > bog-standard compiler and linker options. > > $ objdump -S bt_perf > Idx Name Size VMA LMA File off Algn > .... > 15 .ARM.extab 00000264 0000a7e8 0000a7e8 0000a7e8 2**2 > CONTENTS, ALLOC, LOAD, READONLY, DATA > 16 .ARM.exidx 000002a0 0000aa4c 0000aa4c 0000aa4c 2**2 > CONTENTS, ALLOC, LOAD, READONLY, DATA > 17 .eh_frame 00000004 0000acec 0000acec 0000acec 2**2 > CONTENTS, ALLOC, LOAD, READONLY, DATA I didn't notice anything in particular looking at the commit logs. I'll try and repro when I get a chance _______________________________________________ Libunwind-devel mailing list Libunwind-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/libunwind-devel
