[cjbprime]

I wish I hadn't read this article because now I know that I've been mispronouncing Valgrind for nearly 20 years but I'm not going to stop.

(Kidding. Thanks for Valgrind! I still use it for assessing memory corruption vulnerabilities along with ASan.)

[galangalalgol]

Our pipelines have asan ( and cpp check clang tidy coverity and coverage stuff) but no valgrind, is there something it is good at that we are missing?

[Jason_Gibson]

ASAN on its own doesn't detect uninitialized memory. MSAN can, though. Valgrind is also more than just the memcheck sub-tool - there are others, like Cachegrind, which is a cache and branch-prediction profiler.

https://github.com/google/sanitizers/wiki/AddressSanitizerCo... https://github.com/google/sanitizers/wiki/MemorySanitizer https://valgrind.org/docs/manual/manual.html

[glouwbug]

Yeah, valgrind can report L1/L2 cache misses and report the percentage of branch mispredictions. It also reports the exact number of instructions processed, and how many of those instructions cache missed. It's great for improving small code that needs to be performant.

I'd use asan over valgrind only for memory leaks. It's faster.

[Sesse__]

If you only want memory leaks, LSan will do that for you.

In general, I tend to use ASan for nearly everything I used Valgrind for back in the day; it's faster and usually more precise (Valgrind cannot reliably detect small overflows between stack variables). Valgrind if I cannot recompile, or if ASan doesn't find th issue. Callgrind and Cachegrind never; perf does a much better job, much faster. DHAT never; Heaptrack gives me what I want.

Valgrind was and is a fantastic tool; it became part of my standard toolkit together with the editor, compiler, debugger and build system. But technology has moved on for me.

[gpderetta]

Amen. Between the various sanitizers and perf, I stopped needing valgrind a few years ago.

But when it was the only option it was fantastically useful.

[themulticaster]

If I understand correctly valgrind (cachegrind) reports L1/L2 cache misses based on a simulated CPU/cache model.

On Linux, you can easily instrument real cache events using the very powerful perf suite. There is an overwhelming number of events you can instrument (use perf-list(1) to show them), but a simple example could look like this:

  $ perf stat -d -- sh -c 'find ~ -type f -print | wc -l'
  ^Csh: Interrupt
   Performance counter stats for 'sh -c find ~ -type f -print | wc -l':
  
               47,91 msec task-clock                #    0,020 CPUs utilized
                 599      context-switches          #   12,502 K/sec
                  81      cpu-migrations            #    1,691 K/sec
                 569      page-faults               #   11,876 K/sec
         185.814.947      cycles                    #    3,878 GHz                      (28,71%)
         105.650.405      instructions              #    0,57  insn per cycle           (46,15%)
          22.991.322      branches                  #  479,863 M/sec                    (46,72%)
             643.767      branch-misses             #    2,80% of all branches          (46,14%)
          26.010.223      L1-dcache-loads           #  542,871 M/sec                    (36,80%)
           2.449.173      L1-dcache-load-misses     #    9,42% of all L1-dcache accesses  (29,62%)
             517.052      LLC-loads                 #   10,792 M/sec                    (22,53%)
             133.152      LLC-load-misses           #   25,75% of all LL-cache accesses  (16,02%)
  
         2,403975646 seconds time elapsed
  
         0,005972000 seconds user
         0,046268000 seconds sys

Ignore the command, it's just a placeholder to get meaningful values. The -d flag adds basic cache events, by adding another -d you also get load and load miss events for the dTLB, iTLB and L1i cache.

But as mentioned, you can instrument any event supported by your system. Including very obscure events such as uops_executed.cycles_ge_2_uops_exec (Cycles where at least 2 uops were executed per-thread) or frontend_retired.latency_ge_2_bubbles_ge_2 (Retired instructions that are fetched after an interval where the front-end had at least 2 bubble-slots for a period of 2 cycles which was not interrupted by a back-end stall).

You can also record data using perf-record(1) and inspect them using perf-report(1) or - my personal favorite - the Hotspot tool (https://github.com/KDAB/hotspot).

Sorry for hijacking the discussion a little, but I think perf is an awesome little tool and not as widely known as it should be. IMO, when using it as a profiler (perf-record), it is vastly superior to any language-specific built-in profiler. Unfortunately some languages (such as Python or Haskell) are not a good fit for profiling using perf instrumentation as their stack frame model does not quite map to the C model.

[gkfasdfasdf]

If your tests can take the performance hit, Valgrind would tell you about uninitialized memory reads, which isn't covered by those tools you mentioned. If however, you are able to add MSAN (i.e. able to rebuild the entire product, including dependencies, with -fsanitize=memory) to the pipeline, then you would have the same coverage as Valgrind.

[cjbprime]

The main reason for Valgrind would be if you're working with a binary that you can't recompile to add the ASAN instrumentation.

[stormbrew]

Fwiw I've literally worked with Nicholas (but not on valgrind) and I only learned this today somehow.

[harry8]

I was introduced to valgrind by Andrew Tridgell during the main content of a vaguely famous lecture he gave that finished with the audience collectively writing a shellscript bitkeeper client [1] demonstrating beyond doubt that Tridge had not in any way acted like a "git" when bitkeeper's licenseholder pulled the license for the linux kernel community.

Tridge said words to the effect "if you program in C and you don't aren't using valgrind you flipping should be!" And went on to talk about how some projects like to have a "valgrind clean" build the same way they compile without warnings and that it's a really useful thing. As ever well expressed with examples from samba development.

He was obviously right and I started using valgrind right there in the lecture theatre. apt-get install is a beautiful thing.

He pronounced it val grind like the first part of "value" and "grind" as in grinding coffee beans. I haven't been able to change my pronunciation since then regardless of it being "wrong".

[1] https://lwn.net/Articles/132938/

Corbett's account of this is actually wrong in the lwn link above. Noted by akumria in the comments below it. Every single command and suggestion came from the audience, starting with telnetting to Ted Tso's bitkeeper ip & port that he made available for the demo. Typing help came from the audience as did using netcat and the entire nc command. The audience wrote the bitkeeper client in 2 minutes with tridge doing no more than encouraging, typing and pointing out the "tridge is a wizard reverse engineer who has used his powers for evil" Was clearly just some "wrong thinking." Linus claimed thereafter that Git was named after himself and not Tridge.

[throwawaylinux]

Tridgell is possibly the most intelligent person I've ever met, and I've met Torvalds and a bunch of other Linux developers -- not that they aren't intelligent too, among them might be a challenger to that title.

Tridge has a way of explaining complicated ideas in a way that pares them down to their essence and helps you to understand them that just really struck me (a smart person is able to talk about a complicated thing in a way that makes you feel dumb, a really smart person is able to talk about a complicated thing in a way that makes you feel like a genius). As well as the ability and intellectual curiosity to jump seemingly effortlessly across disciplines.

And he's a fantastic and very entertaining public speaker. Highly recommend any talk he gives.

[dtgriscom]

I've been promoting proper pronunciation of Valgrind at work, an am making passable progress...

[quickthrower2]

Valarie smiled. Is how I will remember it.

That said I sometimes get the "V" tools mixed up (Vagrant, Valgrind, Varnish)

[glandium]

I've known the right pronunciation for about 10 years. I still say it wrong.

[hgs3]

It's giving me flashbacks to the hard G vs soft G in gif image format.

[klyrs]

I learned of the tool from a native German speaker who pronounced it wall-grinned, which is apparently half-right. Like latex, I can't keep the pronunciation straight from one sentence to the next.

[opan]

How do you pronounce it? I hoped it'd be near the start, but several paragraphs in and I'm still not sure.

edit: val as in value + grinned

[koolba]

What other ways are there to (mis)pronounce it?

[dahart]

There are so many amazing ways! ;)

Since it’s an old Norse word, try using Google Translate to hear what happens in Danish, Dutch, German, Icelandic, Norwegian, and Swedish. I don’t know if it’s a modern word in those languages, but Translate is showing translations “election gate” for several languages, and “fall gravel” for Swedish.

According to the audio pronunciations on Translate…

Danish: “vale grint”, long a, hard tapped r, hard d sounds like t

Dutch: sounds like “fall hint” but there’s a slight throaty r in there hard to hear for English speakers, so maybe “hrint”

German: “val grinned”, val like value, grinned with the normal German r

Icelandic: “vall grint”, vall like fall, hard tapped r

Norwegian: “vall grin”, hard tapped r, almost “vall g’din”, silent or nearly silent d/t at the end.

Swedish: “voll grint / g’dint”, hard tapped r, hard d

German is the only one that has “Val” like “value”, all the rest sound more like “fall”. The word valgrind is the door to Valhalla, which means literally “fall hall”, as in hall of the fallen. For that reason, I suspect it makes the most sense to pronounce valgrind like “fall grinned”, but Old Norse might have used val like value, I’m not sure.

BTW Valhalla has an equally amusing number of ways to pronounce it across Germanic languages, “val” sometimes turns into what sound like “fell” instead of “fall”, and in Icelandic the double ell makes it fall-hat-la.

Languages are cool!

[meowface]

Pronouncing the "-grind" like the word "grind". I think that's probably how most English-speakers first assume it's pronounced.

[Buttons840]

Safe to assume many pronounce grind as "grind".

[dietr1ch]

Now you are really on track to mispronounce Valgrind for nearly 21 years :P