[workspace] resolver = "2" members = [ "crates/quicksearch-core", "crates/quicksearch-gui", ] [workspace.package] version = "1.1.0" edition = "2021" license = "GPL-3.0-or-later" authors = ["Jeremy "] repository = "https://code.karsttech.com/jeremy/quick_search.git" # Fat LTO, one codegen unit. This reverses an earlier decision, so both # measurements are kept: the old one was right about what it measured, and it # measured the wrong axis on the wrong kind of build. # # WHAT WAS MEASURED BEFORE, against an *incremental* rebuild of the GUI after # touching core (10.2 s at the defaults): # # lto=thin 67 s search cold 29.9 ms warm best 14.77 ms index cold 459 ms # lto=thin,cgu=1 152 s (build cost alone ruled it out) # lto=fat,cgu=1 200 s search cold 29.2 ms warm best 14.57 ms index cold 479 ms # (defaults) 10 s search cold 30.0 ms warm best 14.92 ms index cold 478 ms # # It concluded that the runtime gain was at the noise floor against a 6.6-19.5x # longer build. Two things were wrong with that as a decision: # # * It never weighed SIZE, which turns out to be where the effect is. # * A 10 s incremental rebuild is the worst possible denominator for a # link-time optimization, because the LTO link is nearly the whole cost and # there is no compile phase to amortize it against. CI never builds that # way; it builds clean. # # RE-MEASURED CLEAN, on 6 cores, stripped `target/*/quicksearch`: # # stripped vs def search cold warm best index cold # (defaults) 28,248,272 - 28.2 ms 14.7 ms 445 ms # cgu=1 25,909,616 -8.3% 28.6 ms 14.8 ms 452 ms # lto=thin 28,233,296 -0.1% (not run: no size effect) # lto=thin,cgu=1 25,991,536 -8.0% (not run: worse than cgu=1 alone) # lto=fat,cgu=1 24,284,912 -14.0% 27.3 ms 14.1 ms 443 ms # # Search is best of three runs; the spreads overlap, so read fat as "3-4% # faster or even", never as a regression. It is both the fastest and by far the # smallest, which is why it wins outright. # # Two surprises worth keeping. `codegen-units = 1` ALONE is worth 2.3 MB - the # old table never isolated it, because every cgu=1 row there also carried LTO. # And `lto = "thin"` alone is worth nothing at all (0.1%), while thin+cgu=1 is # slightly *worse* than cgu=1 by itself. Thin is not a cheaper fat here; it is # a different, useless thing. # # BUILD COST, clean, 6 cores. The second column is what CI actually pays on top # of the binaries, since `cargo test --release --workspace` links every test, # example and bin target - `--release` is `--profile=release`, so this profile # is theirs too: # # bins + all test targets total # (defaults) 143 s 28 s 171 s # cgu=1 158 s 41 s 199 s # lto=fat,cgu=1 198 s 100 s 298 s # # So +127 s on a clean CI run, not the tens of minutes the incremental figure # above implies. Test targets link cheaply because they are small; it is the # 320-crate dependency compile that dominates, and cgu=1 spreads across cores. # # WHAT IS DELIBERATELY NOT SET: # # `strip` would save nothing shipped. The packaging scripts and ci.yml strip the # staged *copy*, which keeps `target/release/` symbolised for `perf` and for the # RUST_BACKTRACE=1 release-test backtraces CI prints, and keeps `--no-strip` on # build-deb.sh and build-appimage.sh meaning something. Setting it here would # move the same 6.5 MB saving to a place where it costs debuggability. # # `panic = "abort"` is the largest win left - it would delete `.gcc_except_table` # (428 KB after LTO) and most of `.eh_frame` (1.33 MB) - and is unavailable for # two independent reasons. `extract/pdf.rs` runs `pdf-extract` inside # `catch_unwind`, so aborting would turn a malformed PDF into a killed process # instead of one skipped file. And cargo forces every dependency to rebuild with # unwind when building tests under an abort profile, so `cargo test --release` # would compile the whole graph a second time. # # Non-PIE would remove most of `.rela.dyn` (1.37 MB) and is rejected on # hardening grounds: this program parses arbitrary user PDFs with a crate known # to panic on malformed input, which is the last place to give up ASLR. # # The vendored OpenSSL (~1.3 MB of `.text`, via SQLCipher) is unreachable by any # profile knob - `openssl-src` pins its own `-O2` - and dropping it would add a # runtime `libcrypto` dependency, which is exactly what the AppImage's # bundles-no-libraries invariant forbids. [profile.release] lto = "fat" codegen-units = 1