[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [RFC PATCH] Makefile: Enable synchronized parallel outp
Michael S. Tsirkin
Re: [Qemu-devel] [RFC PATCH] Makefile: Enable synchronized parallel output when possible
Fri, 22 Jun 2018 06:22:03 +0300
On Thu, Jun 21, 2018 at 11:20:35PM -0300, Philippe Mathieu-Daudé wrote:
> 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’).
> This is the default: all output is sent directly as it is
> generated and no synchronization is performed.
> 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.
> 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.
> 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=
> SUBDIR_MAKEFLAGS=$(if $(V),,--no-print-directory --quiet)
> +ifeq ($(shell test $(firstword $(subst ., ,$(MAKE_VERSION))) -ge 4; echo
> SUBDIR_DEVICES_MAK=$(patsubst %, %/config-devices.mak, $(TARGET_LIST))
> SUBDIR_DEVICES_MAK_DEP=$(patsubst %, %-config-devices.mak.d, $(TARGET_LIST))
I'd probably just use -O. If they change the default it will probably be
to a better one.