From 8a0af16472989543b63264e9e3b24760e85e5d32 Mon Sep 17 00:00:00 2001 From: Aaron Prindle Date: Fri, 18 Aug 2023 11:36:06 -0700 Subject: [PATCH] docs: add more information regarding --use-new-run (#2687) --- README.md | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/README.md b/README.md index 8a924533e..8579d4c5c 100644 --- a/README.md +++ b/README.md @@ -1068,8 +1068,12 @@ Set this flag to indicate which build stage is the target build stage. #### Flag `--use-new-run` -Use the experimental run implementation for detecting changes without requiring -file system snapshots. In some cases, this may improve build performance by 75%. +Use the experimental RUN implementation for detecting changes without requiring +Using this flag enables an experimental implementation of the Run command which does not rely on snapshotting at all. +In this approach, in order to compute which files were changed, a marker file is created before executing the Run command. +Then the entire filesystem is walked (takes ~1-3 seconds for 700Kfiles) to find all files whose ModTime is greater than the marker file. +With this new run command implementation, the total build time is reduced seeing performance improvements in the range of ~75%. This new run mode trades +off accuracy/correctness in some cases (potential for missed files in "snapshot") for improved performance by avoiding the full filesystem snapshots. #### Flag `--verbosity`