> On Dec 21, 2017, at 8:23 AM, Pavel Labath <lab...@google.com> wrote: > > On 21 December 2017 at 10:45, Pavel Labath <lab...@google.com> wrote: >> I'm not sure now whether you're suggesting to use the dsymutil >> approach just to gauge the potential speedup we can obtain and get >> people interested, or as a productized solution. If it's the first one >> then I fully agree with you. Although I think I can see an even >> simpler way to estimate the speedup: build lldb for mac with apple >> indexes disabled and compare its performance to a vanilla one. I'm >> going to see if I can get some numbers on this today. > > > Here's some data I gathered today. What I did was I disabled apple > accelerator table parsing in ObjectFileELF (patch is in the > attachment) and then I compared startup time when debugging lldb with > itself. Specifically I used an Release (optimized) lldb to open a > Debug lldb, set a breakpoint, hit it, display local variables and > backtrace. The precise command is: > $ time opt/bin/lldb -o "br set -n DoExecute" -o "pr la" -o "bt" -o "fr > var" -b -- dbg/bin/lldb -- /bin/ls > I ran the command three times and chose the median result. > > Before I show the measurements I have to give one big disclaimer: The > debugger with accelerator tables disabled does not appear to be fully > functional. Specifically most (all?) of the objc tests in the test > suite hang, and also 50 additional tests fail (the failures seem to be > related to expression evaluation, mostly). However, I think the fact > that the remaining ~2000 tests passed means that we still have been > reading the dwarf parsing functionality is reasonably intact. > > Now, the numbers: > vanilla dSYM > real 0m7.774s > user 0m15.261s > sys 0m1.228s > > > ===== > vanilla no-dSYM > real 0m5.987s > user 0m4.919s > sys 0m0.698s > > > > ===== > no-apple dSYM > real 0m7.616s > user 0m14.812s > sys 0m1.208s > > > ===== > no-apple no-dSYM > real 0m45.520s > user 0m31.096s > sys 0m11.101s > > > > It's not fully clear to me how to interpret this data. The difference > between having the accelerator tables and not is approximately what I > would expect (a lot) in the no-dSYM scenario, and I believe this is > the kind of speedup we should expect on linux. However, there are also > some question marks, like why is the time virtually unchanged in case > we have a dSYM bundle around? Also, the difference between having dSYM > and not is quite large (and opposite to what I would expect) in > "vanilla" case. > <apple.diff>
So results might be wrong because you can't debug /bin/ls and many commands might just not be happening (as soon as you get an error, the command stop happening). /bin/ls is Apple signed and SIP (system integrity protection) will stop you from actually debugging it. Did you disable SIP? _______________________________________________ lldb-dev mailing list lldb-dev@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
