On Sat, Jun 20, 2020 at 5:53 AM Derrick, Jonathan <jonathan.derrick@xxxxxxxxx> wrote: > > On Thu, 2020-06-18 at 18:05 -0700, Matthew Wilcox wrote: > > On Thu, Jun 18, 2020 at 11:52:55PM +0000, Derrick, Jonathan wrote: > > > Hi David, > > > > > > I've been experiencing a performance regression when running a parallel > > > compilation (eg, make -j72) on recent kernels. > > > > I bet you're using a version of make which predates 4.3: > > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0ddad21d3e99c743a3aa473121dc5561679e26bb > > > > I am! > > # make --version > GNU Make 4.2.1 > > > Thank you Matthew! Check your distribution and included patches on top of a vanilla make v4.2. Debian had some important ones I described in [1]. When proposing "make version 4.3" for tc-build - an opportunity to build a llvm-toolchain the easy way - we saw different numbers. I pointed in [1] to the Linus patch Matthew did here. Personally, with switching to Debian's make version 4.3-3 I have seen no big differences when using "make -j3" to build Linux v5.7+. That might be different with "make -j72"... ...can I have SSH access to this machine, please :-), You forgot to tell which Linux version you use. If you are interested please look at closed tc-build issue #72 for our analysis. For tc-build it did not matter - (Debian's) make v4.2 had some slightly better performance. BTW, with that pipe improvements in Linux v5.7 I see some better numbers when using pipebench to benchmark my devices: Example: SanDisk iSSD 16GB root# cat /dev/sdb | pipebench > /dev/null Summary: Piped 14.91 GB in 00h01m25.20s: 179.23 MB/second Before: approx. 100MB/s BTW, I heard of hyperfine benchmark tool the first time when dealing with make performance (see [2]) in ClangBuiltLinux. I would like to see some benchmark numbers with hyperfine from you if you do not mind. Stay OPEN minded and curious. Thanks. - Sedat - [1] https://github.com/ClangBuiltLinux/tc-build/issues/72 [2] https://github.com/sharkdp/hyperfine [3] https://github.com/sharkdp/hyperfine/releases
