Mention that perfs would be affected by prod version

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Théophile Bastian 2018-08-08 14:19:29 +02:00
parent b128ddd571
commit 9e09921c2a

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@ -1014,6 +1014,15 @@ Table~\ref{table:bench_time}.
\caption{Time benchmarking on hackbench}\label{table:bench_time} \caption{Time benchmarking on hackbench}\label{table:bench_time}
\end{table} \end{table}
The performance of \ehelfs{} is probably overestimated, since \ehelfs{} do not
handle all registers from the original DWARF file, and thus the
\prog{libunwind} version must perform more computation. However, this overhead,
although impossible to measure without first implementing supports for every
register, would probably not be that big, since most of the time is spent
finding the relevant row. Support for every DWARF instruction, however, would
not slow down at all the implementation, since every instruction would simply
be compiled to x86\_64 without affecting the already supported code.
It is also worth noting that on the machine described in It is also worth noting that on the machine described in
Section~\ref{ssec:bench_hw}, the compilation of the \ehelfs{} at a level of Section~\ref{ssec:bench_hw}, the compilation of the \ehelfs{} at a level of
\lstc{-O2} needed to run \prog{hackbench}, that is, \prog{hackbench}, \lstc{-O2} needed to run \prog{hackbench}, that is, \prog{hackbench},
@ -1036,6 +1045,11 @@ way smaller \lstc{.eh_frame}, thus, the outlined data is reused only a few
times, compared to \eg{} \prog{libc}, in which the outlined data is reused a times, compared to \eg{} \prog{libc}, in which the outlined data is reused a
lot. lot.
Just as with time performance, the measured compactness would be impacted by
supporting every register, but probably not that much either, since most
columns are concerned with the four supported registers (see
Section~\ref{ssec:instr_cov}).
\begin{table}[h] \begin{table}[h]
\centering \centering
\begin{tabular}{r r r r r r} \begin{tabular}{r r r r r r}