On Sat, Mar 27, 2021 at 9:02 PM Linus Torvalds
wrote:
>
> On Sat, Mar 27, 2021 at 5:08 AM Sedat Dilek wrote:
> >
> > debian-5.10.19 as host-kernel:
> > 11655.755564957 seconds time elapsed
> >
> > dileks-5.12-rc3 plus x86-nops as host-kernel:
> > 11941.439350080 seconds time elapsed
>
> That's
On Sat, Mar 27, 2021 at 5:08 AM Sedat Dilek wrote:
>
> debian-5.10.19 as host-kernel:
> 11655.755564957 seconds time elapsed
>
> dileks-5.12-rc3 plus x86-nops as host-kernel:
> 11941.439350080 seconds time elapsed
That's 2.5% - a huge difference. Particularly since kernel build times
shouldn't
Out of curiosity I tried in my build-environment and my testing-rules
to have comparable numbers...
..without passing "V=1" and "KBUILD_VERBOSE=1" as make-options:
NOTE: Identical linux-config plus LLVM/Clang v12.0.0-rc3.
debian-5.10.19 as host-kernel:
11655.755564957 seconds time elapsed
On Mon, Mar 15, 2021 at 11:14 PM Peter Zijlstra wrote:
>
> On Mon, Mar 15, 2021 at 07:23:29PM +0100, Sedat Dilek wrote:
>
> > You mean something like that ^^?
> >
> > - Sedat -
> >
> > [1]
> > https://git.zx2c4.com/laptop-kernel/commit/?id=116badbe0a18bc36ba90acb8b80cff41f9ab0686
>
> *shudder*,
On Mon, Mar 15, 2021 at 07:23:29PM +0100, Sedat Dilek wrote:
> You mean something like that ^^?
>
> - Sedat -
>
> [1]
> https://git.zx2c4.com/laptop-kernel/commit/?id=116badbe0a18bc36ba90acb8b80cff41f9ab0686
*shudder*, I was more thinking you'd simply add it to you CFLAGS when
building. I
On Mon, Mar 15, 2021 at 7:10 PM Peter Zijlstra wrote:
>
> On Mon, Mar 15, 2021 at 06:04:41PM +0100, Sedat Dilek wrote:
>
> > make V=1 -j4 LLVM=1 LLVM_IAS=1
>
> So for giggles I checked, neither GCC nor LLVM seem to emit prefix NOPs
> when building with -march=sandybridge, they always use MOPL.
>
On Mon, Mar 15, 2021 at 06:04:41PM +0100, Sedat Dilek wrote:
> make V=1 -j4 LLVM=1 LLVM_IAS=1
So for giggles I checked, neither GCC nor LLVM seem to emit prefix NOPs
when building with -march=sandybridge, they always use MOPL.
Furthermore, the kernel explicitly sets: -falign-jumps=1
On Mon, Mar 15, 2021 at 06:19:34PM +0100, Sedat Dilek wrote:
> With my next build I try to apply this.
Your perf tool command should look something like this:
perf stat --repeat 5 --sync --pre=/root/bin/pre-build-kernel.sh -- make -s -j9
LLVM=1 LLVM_IAS=1 bzImage
Also, needless to say, your
On Mon, Mar 15, 2021 at 6:15 PM Borislav Petkov wrote:
>
> On Mon, Mar 15, 2021 at 06:04:41PM +0100, Sedat Dilek wrote:
> > Here some fresh numbers:
>
> Lemme paste my previous reply which still holds true here:
>
> "There's a reason I have -s for silent in the build - printing output
> during
On Mon, Mar 15, 2021 at 06:04:41PM +0100, Sedat Dilek wrote:
> Here some fresh numbers:
Lemme paste my previous reply which still holds true here:
"There's a reason I have -s for silent in the build - printing output
during the build creates a *lot* of variance. And you have excessive
printing
On Sat, Mar 13, 2021 at 2:47 PM Sedat Dilek wrote:
[ ... ]
> Let me look if I will do a selfmade ThinLTO+PGO optimized LLVM
> toolchain v12.0.0-rc3 this weekend.
>
I did it.
Here some fresh numbers:
[ Selfmade LLVM toolchain v12.0.0-rc3 "stage1-only" ]
[ Host-Kernel:
On Sat, Mar 13, 2021 at 2:29 PM Borislav Petkov wrote:
>
> On Sat, Mar 13, 2021 at 01:58:56PM +0100, Sedat Dilek wrote:
> > You can add Debian/experimental APT sources.list ...
>
> I could but I don't expect clang12 to behave any differently here.
>
Agreed in things of build-time.
There were
On Sat, Mar 13, 2021 at 01:58:56PM +0100, Sedat Dilek wrote:
> You can add Debian/experimental APT sources.list ...
I could but I don't expect clang12 to behave any differently here.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
On Sat, Mar 13, 2021 at 1:49 PM Borislav Petkov wrote:
>
> On Sat, Mar 13, 2021 at 01:38:22PM +0100, Sedat Dilek wrote:
> > AFAICS you did a 5 times x86-64 defconfig with dropped pagecache and `make
> > -j9`?
>
> The tailored .config for that particular test box.
>
> > Does your distribution
On Sat, Mar 13, 2021 at 01:38:22PM +0100, Sedat Dilek wrote:
> AFAICS you did a 5 times x86-64 defconfig with dropped pagecache and `make
> -j9`?
The tailored .config for that particular test box.
> Does your distribution offer LLVM/Clang v12.0.0-rc3 (released this
> week) binaries?
The
On Sat, Mar 13, 2021 at 1:15 PM Borislav Petkov wrote:
>
> On Sat, Mar 13, 2021 at 01:10:29PM +0100, Sedat Dilek wrote:
> > Here we go:
> >
> > https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/patch/?id=864b435514b286c0be2a38a02f487aa28d990ef8
>
> That's why I told earlier you to use
On Sat, Mar 13, 2021 at 01:10:29PM +0100, Sedat Dilek wrote:
> Here we go:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/patch/?id=864b435514b286c0be2a38a02f487aa28d990ef8
That's why I told earlier you to use tip/master - that patch is already
in it and all you would've needed
On Sat, Mar 13, 2021 at 9:51 AM Borislav Petkov wrote:
>
> On Sat, Mar 13, 2021 at 06:26:15AM +0100, Sedat Dilek wrote:
> > x86/jump_label: Mark arguments as const to satisfy asm constraints
>
> Where do I find this patch?
>
Here we go:
On Sat, Mar 13, 2021 at 09:49:23AM +0100, Borislav Petkov wrote:
> Lemme rerun here with clang.
clang11 is almost twice as slow as gcc but difference is still
negligible: ~0.6 seconds.
./tools/perf/perf stat --repeat 5 --sync --pre=/root/bin/pre-build-kernel.sh --
make -s -j9 LLVM=1 LLVM_IAS=1
On Sat, Mar 13, 2021 at 06:26:15AM +0100, Sedat Dilek wrote:
> x86/jump_label: Mark arguments as const to satisfy asm constraints
Where do I find this patch?
> x86: Remove dynamic NOP selection
> objtool,x86: Use asm/nops.h
>
> My benchmark was to build a Linux-kernel with LLVM/Clang
On Fri, Mar 12, 2021 at 12:32:53PM +0100, Peter Zijlstra wrote:
> Since ultimate performance of a 10 year old chip (Intel Sandy Bridge, 2011) is
> simply irrelevant today, remove variable NOPs and use NOPL.
Just ran them on my SNB box:
cpu family : 6
model : 45
model name :
On Fri, Mar 12, 2021 at 7:13 PM Sedat Dilek wrote:
>
> On Fri, Mar 12, 2021 at 6:47 PM Steven Rostedt wrote:
> >
> > On Fri, 12 Mar 2021 18:35:45 +0100
> > Sedat Dilek wrote:
> >
> >
> > > Hey Steve, you degraded me to a number :-).
> >
> > It's the internet, everyone is a number.
> >
> > >
> >
On Fri, Mar 12, 2021 at 6:47 PM Steven Rostedt wrote:
>
> On Fri, 12 Mar 2021 18:35:45 +0100
> Sedat Dilek wrote:
>
>
> > Hey Steve, you degraded me to a number :-).
>
> It's the internet, everyone is a number.
>
> >
> > I dunno which Git tree this patchset applies to, but I check if I can
> >
On Fri, 12 Mar 2021 18:35:45 +0100
Sedat Dilek wrote:
> Hey Steve, you degraded me to a number :-).
It's the internet, everyone is a number.
>
> I dunno which Git tree this patchset applies to, but I check if I can
> apply the patchset to my current local Git.
Try Linus's latest.
> Then
On Fri, Mar 12, 2021 at 06:35:45PM +0100, Sedat Dilek wrote:
> Hey Steve, you degraded me to a number :-).
How did he degrade you to a number?! Actually, he went the length to
patiently explain what you could do.
> I dunno which Git tree this patchset applies to, but I check if I can
On Fri, Mar 12, 2021 at 6:26 PM Steven Rostedt wrote:
>
> On Fri, 12 Mar 2021 15:47:26 +0100
> Borislav Petkov wrote:
>
> > On Fri, Mar 12, 2021 at 03:29:48PM +0100, Sedat Dilek wrote:
> > > What does this change exactly mean to/for me?
> >
> > Probably nothing.
> >
> > I would be very surprised
On Fri, 12 Mar 2021 15:47:26 +0100
Borislav Petkov wrote:
> On Fri, Mar 12, 2021 at 03:29:48PM +0100, Sedat Dilek wrote:
> > What does this change exactly mean to/for me?
>
> Probably nothing.
>
> I would be very surprised if it would be at all noticeable for you -
> it's not like the kernel
On Fri, Mar 12, 2021 at 03:29:48PM +0100, Sedat Dilek wrote:
> What does this change exactly mean to/for me?
Probably nothing.
I would be very surprised if it would be at all noticeable for you -
it's not like the kernel is executing long streams of NOPs in fast
paths.
--
Regards/Gruss,
On Fri, Mar 12, 2021 at 1:00 PM Peter Zijlstra wrote:
>
> Hi!
>
> A while ago Steve complained about x86 being weird for having different NOPs
> [1]
>
> Having cursed the same thing before, I figured it was time to look at the NOP
> situation.
>
> 32bit simply isn't a performance target anymore,
Hi!
A while ago Steve complained about x86 being weird for having different NOPs [1]
Having cursed the same thing before, I figured it was time to look at the NOP
situation.
32bit simply isn't a performance target anymore, so all we need is a set of
NOPs that works on all.
x86_64 has two main
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