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From: |
Ludovic Courtès |
Date: |
Tue, 28 Nov 2023 10:26:20 -0500 (EST) |
branch: master
commit 87a6d6ea7ae79fdf487bbcfd44bb3dce2d7c6e82
Author: Ludovic Courtès <ludo@gnu.org>
AuthorDate: Tue Nov 28 15:51:38 2023 +0100
remote-worker: Correctly compute parallelism per worker.
Fixes <https://issues.guix.gnu.org/67502>.
Since ‘run-fibers’ binds each thread to one core by default,
‘current-processor-count’ when called from within ‘run-fibers’ on a
machine with 4 or fewer cores would always return 1.
* src/cuirass/scripts/remote-worker.scm (worker-management-thunk): Add
‘cpu-count’ parameter and use it instead of calling
‘current-processor-count’.
(cuirass-remote-worker): Call ‘current-processor-count’ outside
‘run-fibers’ and pass the result to ‘worker-management-thunk’.
---
src/cuirass/scripts/remote-worker.scm | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/src/cuirass/scripts/remote-worker.scm
b/src/cuirass/scripts/remote-worker.scm
index c34456c..83f458a 100644
--- a/src/cuirass/scripts/remote-worker.scm
+++ b/src/cuirass/scripts/remote-worker.scm
@@ -406,16 +406,15 @@ process can use up to PARALLELISM cores."
(loop)))))))
-(define (worker-management-thunk channel systems)
+(define (worker-management-thunk channel systems cpu-count)
"Return a thunk that reads from CHANNEL requests to start new workers for
-SYSTEMS."
+SYSTEMS. CPU-COUNT is the total number of CPU cores available on the system,
+to be distributed among all the workers."
(lambda ()
(let loop ()
(match (get-message channel)
(`(start-workers ,count ,server ,local-address)
- (let ((parallelism (max (ceiling-quotient (current-processor-count)
- count)
- 1)))
+ (let ((parallelism (max (ceiling-quotient cpu-count count) 1)))
(log-info
"starting ~a workers (parallelism: ~a cores) for server at ~a"
count parallelism (server-address server))
@@ -469,6 +468,7 @@ exiting."
(server-address (assoc-ref opts 'server))
(systems (assoc-ref opts 'systems))
(urls (assoc-ref opts 'substitute-urls))
+ (cpu-count (current-processor-count)) ;call it before 'run-fibers'
(user (assoc-ref opts 'user))
(public-key
(read-file-sexp
@@ -532,7 +532,8 @@ exiting."
(lambda ()
;; Spawn the fiber that'll actually create workers as it receives
;; requests on MANAGEMENT-CHANNEL.
- (spawn-fiber (worker-management-thunk management-channel systems))
+ (spawn-fiber
+ (worker-management-thunk management-channel systems cpu-count))
;; This program registers roots for successful build results.
;; Normally these build results are sent right away to 'cuirass