216 lines
10 KiB
Plaintext
216 lines
10 KiB
Plaintext
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* blog posts
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- http://jmoiron.net/blog/go-performance-tales/
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- use integer map keys if possible
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- hard to compete with Go's map implementation; esp. if your data structure has lots of pointer chasing
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- aes-ni instructions make string hashing much faster
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- prefer structs to maps if you know the map keys (esp. coming from perl, etc)
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- channels are useful, but slow; raw atomics can help with performance
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- cgo has overhead
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- profile before optimizing
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- http://slideshare.net/cloudflare/go-profiling-john-graham-cumming ( https://www.youtu.be/_41bkNr7eik )
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- don't waste programmer cycles saving the wrong CPU cycles (or memory allocations)
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- bash$ time; time.Now()/time.Since(); pprof.StartCPUProfile/pprof.StopCPUProfile; go tool pprof http://.../profile
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- bash$ ps; runtime.ReadMemStats(); runtime.WriteHeapProfile(); go tool pprof http://.../heap
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- slice operations are sometimes O(n)
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- https://golang.org/pkg/runtime/debug/
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- sync.Pool (basically)
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- https://methane.github.io/2015/02/reduce-allocation-in-go-code
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- 1. correctness is important
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- 2. BenchmarkXXX with b.ReportAllocs() (or -benchmem when running)
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- 3. allocfreetrace=1 produces stack trace on every allocation
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- strategies:
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- avoid string concat; use []byte+append() (+strconv.AppendInt(), ...)
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- benchcmp
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- avoid time.Format
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- avoid range when iterating strings ([]rune conversion + utf8 decoding)
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- can append string to []byte
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- write two versions, one for string, one for []byte (avoids conversion+copy (sometimes...))
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- reuse existing buffers instead of creating new ones
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- http://bravenewgeek.com/so-you-wanna-go-fast/
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- performance fast vs. delivery fast; make the right decision
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- lock-free ring buffer vs. channels: faster except with GOMAXPROCS=1
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- defer has a cost (allocation+cpu)
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BenchmarkMutexDeferUnlock-8 20000000 96.6 ns/op
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BenchmarkMutexUnlock-8 100000000 19.5 ns/op
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- reflection+json
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- ffjson avoids reflection
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- msgp avoids json
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- interfaces have dynamic dispatch which can't be inlined
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- => use concrete types (+ code duplication)
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- heap vs. stack; escape analysis
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- lots of short-lived objects is expensive for the gc
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- sync.Pool reuses objects *between* gc runs
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- you need your own free list to hold onto things between gc runs
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(but now you're subverting the purpose of a garbage collector)
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- false sharing
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- custom lock-free data structures: fast but *hard*
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- "Speed comes at the cost of simplicity, at the cost of development time, and at the cost of continued maintenance. Choose wisely."
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- https://software.intel.com/en-us/blogs/2014/05/10/debugging-performance-issues-in-go-programs
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- http://blog.golang.org/profiling-go-programs
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- https://medium.com/%40hackintoshrao/daily-code-optimization-using-benchmarks-and-profiling-in-golang-gophercon-india-2016-talk-874c8b4dc3c5
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- If you're writing benchmarks, read http://dave.cheney.net/2013/06/30/how-to-write-benchmarks-in-go
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- cache line explanation: http://mechanitis.blogspot.com/2011/07/dissecting-disruptor-why-its-so-fast_22.html
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- avoiding false sharing: http://www.drdobbs.com/parallel/eliminate-false-sharing/217500206
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- how does this translate to go? http://www.catb.org/esr/structure-packing/
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- https://en.wikipedia.org/wiki/Amdahl%27s_law
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- https://github.com/ardanlabs/gotraining/tree/master/topics/profiling
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- https://github.com/ardanlabs/gotraining/tree/master/topics/benchmarking
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- http://dave.cheney.net/2015/11/29/a-whirlwind-tour-of-gos-runtime-environment-variables
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- https://github.com/davecheney/high-performance-go-workshop
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- Mutex profile: https://rakyll.org/mutexprofile
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- https://segment.com/blog/allocation-efficiency-in-high-performance-go-services/
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- http://brendanjryan.com/2018/01/15/go-benchmarks.html
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- https://lemire.me/blog/2018/01/16/microbenchmarking-calls-for-idealized-conditions/
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cgo:
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cgo has overhead
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(which has only gotten more expensive over time) -- ~200 ns/call
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(reduced in 1.8 to <100ns; still not free)
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ssa backend means less difference in codegen
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really think if you want cgo: http://dave.cheney.net/2016/01/18/cgo-is-not-go
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https://www.youtube.com/watch?v=lhMhApWQp2E : cgo gophercon
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cgo performance tracking bug: https://github.com/golang/go/issues/9704
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videos:
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https://gophervids.appspot.com/#tags=optimization
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-- figure out which of these are specifically worth listing
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"Profiling and Optimizng Go" (Uber)
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https://www.youtube.com/watch?v=N3PWzBeLX2M
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https://go-talks.appspot.com/github.com/davecheney/presentations/writing-high-performance-go.slide
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https://www.youtube.com/watch?v=zWp0N9unJFc
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Björn Rabenstein
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https://docs.google.com/presentation/d/1Zu0BdbhMRar7ycEwDi8jepGokTXTDXlKFf7C13tusuI/edit
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https://www.youtube.com/watch?v=ZuQcbqYK0BY
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https://go-talks.appspot.com/github.com/mkevac/golangmoscow2016/gomeetup.slide
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CppCon 2014: Chandler Carruth "Efficiency with Algorithms, Performance with Data Structures"
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https://www.youtube.com/watch?v=fHNmRkzxHWs
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Performance Engineering of Software Systems
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http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-172-performance-engineering-of-software-systems-fall-2010/
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https://talks.golang.org/2013/highperf.slide#1
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Machine Architecture: Things Your Programming Language Never Told You
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https://www.youtube.com/watch?v=L7zSU9HI-6I
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7 Ways to Profile Go Applications
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https://www.youtube.com/watch?v=2h_NFBFrciI
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dotGo 2016 - Damian Gryski - Slices: Performance through cache-friendliness
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https://www.youtube.com/watch?v=jEG4Qyo_4Bc
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Performance Bugs
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https://www.youtube.com/watch?v=89qiHoDjeDg
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The Hurricane's Butterfly: Debugging Pathologically Performing Systems
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https://www.youtube.com/watch?v=7AO4wz6gI3Q
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"So You Wanna Go Fast?" by Tyler Treat
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https://www.youtube.com/watch?v=DJ4d_PZ6Gns
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GopherCon 2017: Peter Bourgon - Evolutionary Optimization with Go
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https://www.youtube.com/watch?v=ha8gdZ27wMo
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asm:
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https://golang.org/doc/asm
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https://goroutines.com/asm
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http://www.doxsey.net/blog/go-and-assembly
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https://www.youtube.com/watch?v=9jpnFmJr2PE
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https://blog.gopheracademy.com/advent-2016/peachpy/
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https://blog.sgmansfield.com/2017/04/a-foray-into-go-assembly-programming/
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http://lemire.me/blog/2016/12/21/performance-overhead-when-calling-assembly-from-go/
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http://davidwong.fr/goasm/
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minio posts + tooling
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https://github.com/teh-cmc/go-internals/blob/master/chapter1_assembly_primer/README.md
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https://blog.hackercat.ninja/post/quick_intro_to_go_assembly/
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posts:
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http://www.eecs.berkeley.edu/~rcs/research/interactive_latency.html
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https://arxiv.org/abs/1509.05053 (array layouts for comparison-based searching)
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http://grokbase.com/t/gg/golang-nuts/155ea0t5hf/go-nuts-after-set-gomaxprocs-different-machines-have-different-bahaviors-some-speed-up-some-slow-down
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http://grokbase.com/t/gg/golang-nuts/14138jw64s/go-nuts-concurrent-read-write-of-different-parts-of-a-slice
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Escape Analysis Flaws
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https://docs.google.com/document/d/1CxgUBPlx9iJzkz9JWkb6tIpTe5q32QDmz8l0BouG0Cw/preview
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https://hackernoon.com/optimizing-optimizing-some-insights-that-led-to-a-400-speedup-of-powerdns-5e1a44b58f1c
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http://leto.net/docs/C-optimization.php
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http://www.stochasticlifestyle.com/algorithm-efficiency-comes-problem-information/
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tools:
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https://godoc.org/github.com/aclements/go-perf
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https://godoc.org/x/perf/cmd/benchstat
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https://github.com/rakyll/gom
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https://github.com/tam7t/sigprof
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https://github.com/aybabtme/dpprof
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https://github.com/wblakecaldwell/profiler
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https://github.com/MiniProfiler/go
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https://perf.wiki.kernel.org/index.php/Main_Page
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https://github.com/dominikh/go-structlayout
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http://www.brendangregg.com/perf.html
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https://github.com/davecheney/gcvis
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https://github.com/pavel-paulau/gcterm
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https://github.com/jonlawlor/benchls
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pprof:
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https://rakyll.org/pprof-ui/
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https://rakyll.org/profiler-labels/
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https://rakyll.org/custom-profiles/
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trace:
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https://making.pusher.com/go-tool-trace/
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https://www.youtube.com/watch?v=mmqDlbWk_XA
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https://www.youtube.com/watch?v=nsM_m4hZ-bA
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https://blog.gopheracademy.com/advent-2017/go-execution-tracer/
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papers:
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https://www.akkadia.org/drepper/cpumemory.pdf
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https://software.intel.com/sites/default/files/article/392271/aos-to-soa-optimizations-using-iterative-closest-point-mini-app.pdf
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optimization guides:
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http://developer.amd.com/resources/developer-guides-manuals/
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http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.uan0015b/index.html
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https://www-ssl.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-optimization-manual.html
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https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines.html#S-performance
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https://github.com/fenbf/AwesomePerfCpp
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https://www.kernel.org/pub/linux/kernel/people/paulmck/perfbook/perfbook.2017.11.22a.pdf
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stackoverflow:
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https://stackoverflow.com/questions/19397699/why-struct-with-padding-fields-works-faster/19397791#19397791
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https://stackoverflow.com/questions/10017026/no-speedup-in-multithread-program/10017482#10017482
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practice:
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https://twitter.com/dgryski/status/584682584942194689
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distributed system design: (out of scope for this book)
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http://highscalability.com/blog/2010/12/20/netflix-use-less-chatty-protocols-in-the-cloud-plus-26-fixes.html
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books:
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Writing Efficient Programs
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Algorithm Engineering: https://www.springer.com/gp/book/9783642148651
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http://www.cs.tufts.edu/~nr/cs257/archive/don-knuth/empirical-fortran.pdf
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Usborne: Programming Tricks and Skills
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https://drive.google.com/file/d/0Bxv0SsvibDMTdElPMHF5NVpmU0U/view
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Quotes: (Bumper Sticker Computer Science)
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[The First Rule of Program Optimization] Don't do it.
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[The Second Rule of Program Optimization---For experts only] Don't do it yet.
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Michael Jackson
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Michael Jackson Systems Ltd.
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The key to performance is elegance, not battalions of special cases.
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— Jon Bentley and Doug McIlroy
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You’re bound to be unhappy if you optimize everything.
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— Donald Knuth
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