| Message ID | 20190611180513.30772-1-mcroce@redhat.com |
|---|---|
| State | Rejected |
| Delegated to: | David Ahern |
| Headers | show |
| Series | [iproute2-next] Makefile: pass -pipe to the compiler | expand |
On Tue, 11 Jun 2019 20:05:13 +0200 Matteo Croce <mcroce@redhat.com> wrote: > Pass the -pipe option to GCC, to use pipes instead of temp files. > On a slow AMD G-T40E CPU we get a non negligible 6% improvement > in build time. > > real 1m15,111s > user 1m2,521s > sys 0m12,465s > > real 1m10,861s > user 1m2,520s > sys 0m12,901s > > Signed-off-by: Matteo Croce <mcroce@redhat.com> Why bother, on my machine (make -j12). Before real 0m6.320s user 0m30.674s sys 0m3.649s After (with -pipe) real 0m6.158s user 0m31.197s sys 0m3.532s So it is slower. Get a faster disk :-) Maybe allow "EXTRA_CFLAGS" to be passed to Makefile for those that have a burning need for this.
On Tue, Jun 11, 2019 at 9:28 PM Stephen Hemminger <stephen@networkplumber.org> wrote: > > On Tue, 11 Jun 2019 20:05:13 +0200 > Matteo Croce <mcroce@redhat.com> wrote: > > > Pass the -pipe option to GCC, to use pipes instead of temp files. > > On a slow AMD G-T40E CPU we get a non negligible 6% improvement > > in build time. > > > > real 1m15,111s > > user 1m2,521s > > sys 0m12,465s > > > > real 1m10,861s > > user 1m2,520s > > sys 0m12,901s > > > > Signed-off-by: Matteo Croce <mcroce@redhat.com> > > Why bother, on my machine (make -j12). > > Before > real 0m6.320s > user 0m30.674s > sys 0m3.649s > > > After (with -pipe) > real 0m6.158s > user 0m31.197s > sys 0m3.532s > > > So it is slower. Get a faster disk :-) > I did it :) root@apu:~# hdparm -t /dev/sda /dev/sda: Timing buffered disk reads: 1086 MB in 3.00 seconds = 361.58 MB/sec No change at all thought. It's really a CPU bound job, and this machine is not a number cruncher: root@apu:~# dd if=/dev/zero bs=1G count=1 status=none |time -p sha1sum 2a492f15396a6768bcbca016993f4b4c8b0b5307 - real 16.00 user 12.38 sys 2.05 I think that the slight increase is due to the fact that the processes starts in parallel, instead of being serialized. > Maybe allow "EXTRA_CFLAGS" to be passed to Makefile for those that > have a burning need for this. Just out of curiosity, I checked the linux history repo to discover when it was introduced in the kernel, it tooks me a while to really find it: Linux-0.99.13k (September 19, 1993)
diff --git a/Makefile b/Makefile index 48f469b0..6c35e7c2 100644 --- a/Makefile +++ b/Makefile @@ -48,7 +48,7 @@ HOSTCC ?= $(CC) DEFINES += -D_GNU_SOURCE # Turn on transparent support for LFS DEFINES += -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -CCOPTS = -O2 +CCOPTS = -O2 -pipe WFLAGS := -Wall -Wstrict-prototypes -Wmissing-prototypes WFLAGS += -Wmissing-declarations -Wold-style-definition -Wformat=2
Pass the -pipe option to GCC, to use pipes instead of temp files. On a slow AMD G-T40E CPU we get a non negligible 6% improvement in build time. real 1m15,111s user 1m2,521s sys 0m12,465s real 1m10,861s user 1m2,520s sys 0m12,901s Signed-off-by: Matteo Croce <mcroce@redhat.com> --- Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)