| Message ID | 1339466983-19786-8-git-send-email-ntl@pobox.com |
|---|---|
| State | Superseded |
| Headers | show |
On 06/12/12 04:09, Nathan Lynch wrote: > When BR2_JLEVEL is 0, set PARALLEL_JOBS to the number of CPUs > detected. This allows one to more or less fully utilize the host > system without manually tuning the configuration. In my experience, you need 2 times the number of CPUs to fully utilize the processor because most compilations have long iowait latencies. Otherwise, looks good. Regards, Arnout
On Thu, 2012-06-14 at 01:27 +0200, Arnout Vandecappelle wrote: > On 06/12/12 04:09, Nathan Lynch wrote: > > When BR2_JLEVEL is 0, set PARALLEL_JOBS to the number of CPUs > > detected. This allows one to more or less fully utilize the host > > system without manually tuning the configuration. > > In my experience, you need 2 times the number of CPUs to fully utilize > the processor because most compilations have long iowait latencies. Yeah. I'm happy to make this change, assuming others agree? Thanks for having a look!
>>>>> "Nathan" == Nathan Lynch <ntl@pobox.com> writes: >> In my experience, you need 2 times the number of CPUs to fully utilize >> the processor because most compilations have long iowait latencies. Nathan> Yeah. I'm happy to make this change, assuming others agree? I was going to say something like that as well, so yes please.
On Thu, 2012-06-14 at 08:07 +0200, Peter Korsgaard wrote: > >>>>> "Nathan" == Nathan Lynch <ntl@pobox.com> writes: > > >> In my experience, you need 2 times the number of CPUs to fully utilize > >> the processor because most compilations have long iowait latencies. > > Nathan> Yeah. I'm happy to make this change, assuming others agree? > > I was going to say something like that as well, so yes please. Certainly. Is an update of patch #7 acceptable or shall I re-send the series?
On Thu, Jun 14, 2012 at 01:27:05AM +0200, Arnout Vandecappelle wrote: > In my experience, you need 2 times the number of CPUs to fully utilize > the processor because most compilations have long iowait latencies. Unless you have little memory, this is no longer true, and as some compilations can eat a lot of memory, doubling their number reduces the amount of available page cache, potentially increasing the amount of I/O. Using the number of available processors should be just fine.
>>>>> "Nathan" == Nathan Lynch <ntl@pobox.com> writes: Nathan> On Thu, 2012-06-14 at 08:07 +0200, Peter Korsgaard wrote: >> >>>>> "Nathan" == Nathan Lynch <ntl@pobox.com> writes: >> >> >> In my experience, you need 2 times the number of CPUs to fully utilize >> >> the processor because most compilations have long iowait latencies. >> Nathan> Yeah. I'm happy to make this change, assuming others agree? >> >> I was going to say something like that as well, so yes please. Nathan> Certainly. Is an update of patch #7 acceptable or shall I Nathan> re-send the series? Just #7 (with a clearly marked [PATCHv2] in subject) is fine if that's the only change since last time.
diff --git a/Config.in b/Config.in index 95c2e8c..3745255 100644 --- a/Config.in +++ b/Config.in @@ -178,10 +178,12 @@ config BR2_DEBIAN_MIRROR endmenu config BR2_JLEVEL - int "Number of jobs to run simultaneously" - default "2" + int "Number of jobs to run simultaneously (0 for auto)" + default "0" help - Number of jobs to run simultaneously + Number of jobs to run simultaneously. If 0, determine + automatically according to number of CPUs on the host + system. config BR2_CCACHE bool "Enable compiler cache" diff --git a/package/Makefile.in b/package/Makefile.in index 9177a1b..a9d2771 100644 --- a/package/Makefile.in +++ b/package/Makefile.in @@ -6,7 +6,11 @@ HOSTMAKE=$(MAKE) endif HOSTMAKE :=$(shell which $(HOSTMAKE) || type -p $(HOSTMAKE) || echo make) +ifeq ($(BR2_JLEVEL),0) +PARALLEL_JOBS:=$(shell getconf _NPROCESSORS_ONLN 2>/dev/null || echo 1) +else PARALLEL_JOBS:=$(BR2_JLEVEL) +endif MAKE1:=$(HOSTMAKE) -j1 MAKE:=$(HOSTMAKE) -j$(PARALLEL_JOBS)
When BR2_JLEVEL is 0, set PARALLEL_JOBS to the number of CPUs detected. This allows one to more or less fully utilize the host system without manually tuning the configuration. Also make 0 the default value for BR2_JLEVEL. Signed-off-by: Nathan Lynch <ntl@pobox.com> --- Config.in | 8 +++++--- package/Makefile.in | 4 ++++ 2 files changed, 9 insertions(+), 3 deletions(-)