Merge branch 'master' into patch-2

Author: axgillies

_layouts/blog.html

@@ -20,7 +20,7 @@ <h1>{{page.title}}</h1>
     title="Subscribe to Abseil Blog &amp; Tips"
     rel="alternate"
     type="application/rss+xml">
-    <img src="//feedburner.google.com/fb/images/pub/feed-icon32x32.png"
+    <img src="//gstatic.com/ac/dashboard/feedburner-32.png"
          alt="Subscribe to the Abseil Blog" style="border:0;">
     </img>
 </a>

_layouts/fast.html

@@ -21,7 +21,7 @@ <h1>{{page.title}}</h1>
     title="Subscribe to Abseil Blog &amp; Tips"
     rel="alternate"
     type="application/rss+xml">
-    <img src="//feedburner.google.com/fb/images/pub/feed-icon32x32.png"
+    <img src="//gstatic.com/ac/dashboard/feedburner-32.png"
          alt="Subscribe to the Abseil Blog" style="border:0;">
     </img>
 </a>

_layouts/tips.html

@@ -21,7 +21,7 @@ <h1>{{page.title}}</h1>
     title="Subscribe to Abseil Blog &amp; Tips"
     rel="alternate"
     type="application/rss+xml">
-    <img src="//feedburner.google.com/fb/images/pub/feed-icon32x32.png"
+    <img src="//gstatic.com/ac/dashboard/feedburner-32.png"
          alt="Subscribe to the Abseil Blog" style="border:0;">
     </img>
 </a>

_posts/2018-02-15-totw-88.md

@@ -104,7 +104,7 @@ variable?", both to follow in your own code and to cite in your code reviews:
   ```cpp
   // Bad code
 
-  // Could invoke an intializer list constructor, or a two-argument constructor.
+  // Could invoke an initializer list constructor, or a two-argument constructor.
   Frobber frobber{size, &bazzer_to_duplicate};
 
   // Makes a vector of two doubles.

_posts/2018-09-28-totw-152.md

@@ -81,7 +81,7 @@ TEST(MyType, SupportsAbslHash) {
 }
 </pre>
 
-`absl::VerifyTypeImplementsAbslHashCorrectly` also supports testing heterogenous
+`absl::VerifyTypeImplementsAbslHashCorrectly` also supports testing heterogeneous
 lookup and custom equality operators.
 
 Intrigued and want to know more? Read up at

_posts/2023-02-15-totw-198.md

@@ -132,7 +132,7 @@ readable code. Take the following example:
 // with std::in_place.
 std::optional<Foo> with_tag(std::in_place, 5, 10);
 
-// Here the intent is clearer: make an optional Foo by providing these argments.
+// Here the intent is clearer: make an optional Foo by providing these arguments.
 std::optional<Foo> with_factory = std::make_optional<Foo>(5, 10);
 </pre>
 

_posts/2023-03-02-fast-21.md

@@ -12,7 +12,7 @@ Originally posted as Fast TotW #21 on January 16, 2020
 
 *By [Paul Wankadia](mailto:junyer@google.com) and [Darryl Gove](mailto:djgove@google.com)*
 
-Updated 2023-03-02
+Updated 2024-10-21
 
 Quicklink: [abseil.io/fast/21](https://abseil.io/fast/21)
 

_posts/2023-03-02-fast-39.md

@@ -12,7 +12,7 @@ Originally posted as Fast TotW #39 on January 22, 2021
 
 *By [Chris Kennelly](mailto:ckennelly@google.com) and [Alkis Evlogimenos](mailto:alkis@evlogimenos.com)*
 
-Updated 2023-10-10
+Updated 2025-03-24
 
 Quicklink: [abseil.io/fast/39](https://abseil.io/fast/39)
 
@@ -146,14 +146,14 @@ would "reduce" the
 [data center tax](https://static.googleusercontent.com/media/research.google.com/en//pubs/archive/44271.pdf),
 but we would actually hurt [application productivity](/fast/7)-per-CPU. Time we
 spend in malloc is
-[less important than application performance](https://research.google/pubs/pub50370.pdf).
+[less important than application performance](https://storage.googleapis.com/gweb-research2023-media/pubtools/6170.pdf).
 
 Trace-driven simulations with hardware-validated architectural simulators showed
 the prefetched data was frequently used. Additionally, it is better to stall on
 a TLB miss at the prefetch site--which has no dependencies, than to stall at the
 point of use.
 
-## Pitfalls
+## Pitfalls {#pitfalls}
 
 There are a number of things that commonly go wrong when writing benchmarks. The
 following is a non-exhaustive list:
@@ -175,15 +175,23 @@ following is a non-exhaustive list:
     [Stabilizer (by Berger, et. al.)](https://people.cs.umass.edu/~emery/pubs/stabilizer-asplos13.pdf)
     deliberately perturb these parameters to improve benchmarking statistical
     quality.
+*   Sensitivity to stack alignment. Changes anywhere in the stack--added/removed
+    variables, better (or worse) spilling due to compiler optimizations,
+    etc.--can affect the alignment at the start of the function-under-test. This
+    has been seen to produce 20% performance swings.
 *   Representative data. The data in the benchmark needs to be "similar" to the
     data in production - for example, imagine having short strings in the
     benchmark, and long strings in the fleet. This also extends to the code
     paths in the benchmarks being similar to the code paths that the application
-    exercises.
+    exercises. This is a common pain point for macrobenchmarks too. A loadtest
+    may cover certain request types, rather than all of those seen by production
+    servers.
+
 *   Benchmarking the right code. It's very easy to introduce code into the
     benchmark that's not present in the real workload. For example, using a
     random number generator's cost for a benchmark could exceed the cost of the
     work being benchmarked.
+
 *   Being aware of steady state vs dynamic behaviour. For more complex
     benchmarks it's easy to produce something that converges to a steady state -
     for example if it has a constant arrival rate and service time. Production

_posts/2023-03-02-fast-53.md

@@ -12,7 +12,7 @@ Originally posted as Fast TotW #53 on October 14, 2021
 
 *By [Mircea Trofin](mailto:mtrofin@google.com)*
 
-Updated 2023-09-04
+Updated 2024-11-19
 
 Quicklink: [abseil.io/fast/53](https://abseil.io/fast/53)
 

_posts/2023-03-02-fast-9.md

@@ -12,7 +12,7 @@ Originally posted as Fast TotW #9 on June 24, 2019
 
 *By [Chris Kennelly](mailto:ckennelly@google.com)*
 
-Updated 2023-10-10
+Updated 2025-03-27
 
 Quicklink: [abseil.io/fast/9](https://abseil.io/fast/9)
 
@@ -64,7 +64,7 @@ Prior to cleanups, the implementations weren't the same.
     working around a
     [false dependency bug](https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62011)
     in some processors.
-*   When the compiler builtin is used (the "slow" version), we actually end up
+*   When the compiler built-in is used (the "slow" version), we actually end up
     with a better sequence of machine code and can perform stronger
     optimizations at compile-time around constant folding.