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[Qemu-devel] [RFC PATCH] Makefile: Enable synchronized parallel output w
From: |
Philippe Mathieu-Daudé |
Subject: |
[Qemu-devel] [RFC PATCH] Makefile: Enable synchronized parallel output when possible |
Date: |
Thu, 21 Jun 2018 23:20:35 -0300 |
The '--output-sync' option is available since GNU make 4.0.
5.4.1 Output During Parallel Execution
When running several recipes in parallel the output from each
recipe appears as soon as it is generated, with the result that
messages from different recipes may be interspersed, sometimes
even appearing on the same line. This can make reading the output
very difficult.
To avoid this you can use the ‘--output-sync’ (‘-O’) option. This
option instructs make to save the output from the commands it
invokes and print it all once the commands are completed.
Additionally, if there are multiple recursive make invocations
running in parallel, they will communicate so that only one of
them is generating output at a time.
There are four levels of granularity when synchronizing output,
specified by giving an argument to the option (e.g., ‘-Oline’
or ‘--output-sync=recurse’).
none
This is the default: all output is sent directly as it is
generated and no synchronization is performed.
line
Output from each individual line of the recipe is grouped
and printed as soon as that line is complete. If a recipe
consists of multiple lines, they may be interspersed with
lines from other recipes.
target
Output from the entire recipe for each target is grouped and
printed once the target is complete. This is the default if
the --output-sync or -O option is given with no argument.
recurse
Output from each recursive invocation of make is grouped and
printed once the recursive invocation is complete.
Regardless of the mode chosen, the total build time will be the
same. The only difference is in how the output appears.
Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
---
Maybe 'line' is better for workstation and 'target/recurse' for
unattended builds.
doc: https://www.gnu.org/software/make/manual/html_node/Parallel-Output.html
---
Makefile | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/Makefile b/Makefile
index e46f2b625a..e94c687afe 100644
--- a/Makefile
+++ b/Makefile
@@ -367,6 +367,10 @@ DOCS=
endif
SUBDIR_MAKEFLAGS=$(if $(V),,--no-print-directory --quiet)
BUILD_DIR=$(BUILD_DIR)
+ifeq ($(shell test $(firstword $(subst ., ,$(MAKE_VERSION))) -ge 4; echo
$$?),0)
+SUBDIR_MAKEFLAGS+=--output-sync=target
+endif
+
SUBDIR_DEVICES_MAK=$(patsubst %, %/config-devices.mak, $(TARGET_LIST))
SUBDIR_DEVICES_MAK_DEP=$(patsubst %, %-config-devices.mak.d, $(TARGET_LIST))
--
2.18.0.rc2
- [Qemu-devel] [RFC PATCH] Makefile: Enable synchronized parallel output when possible,
Philippe Mathieu-Daudé <=