From: Peter Zijlstra <peterz@infradead.org>
To: Nadav Amit <namit@vmware.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"luto@kernel.org" <luto@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/5] x86/percpu semantics and fixes
Date: Sun, 10 Mar 2019 13:46:50 +0100 [thread overview]
Message-ID: <20190310124650.GA6840@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20190308205637.GC2482@worktop.programming.kicks-ass.net>
On Fri, Mar 08, 2019 at 09:56:37PM +0100, Peter Zijlstra wrote:
> Anyway, can anybody explain percpu_stable_op() vs percpu_from_op() ?
>
> I'm thinking of a variant of Linus' patch, but I'm confused about the
> above.
So whatever I tried with +m only made things worse and always affects
thousands of symbols.
Now, afaict the whole percpu_stable_op thing is an ugly hack becaues some
earlier compiler would not CSE the regular percpu_from_op. But since it
does do that today; esp. after my first patch, I tried implementing
this_cpu_read_stable() with percpu_from_op() (no volatile, obv).
That also affects _lots_ of sites, but also significantly shrinks the
kernel image.
It's 2307 symbols affected, but:
17642871 2157438 747808 20548117 1398a15 defconfig-build1/vmlinux.o (patch 1)
17639081 2157438 747808 20544327 1397b47 defconfig-build0/vmlinux.o (patch 1 - percpu_stable_op)
So I think I'll add a patch removing percpu_stable_op and all its users.
next prev parent reply other threads:[~2019-03-10 12:47 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-27 10:12 [PATCH 0/5] x86/percpu semantics and fixes Peter Zijlstra
2019-02-27 10:12 ` [PATCH 1/5] x86/percpu: Differentiate this_cpu_{}() and __this_cpu_{}() Peter Zijlstra
2019-02-27 16:14 ` Linus Torvalds
2019-02-27 16:48 ` Peter Zijlstra
2019-02-27 17:17 ` Linus Torvalds
2019-02-27 17:34 ` Peter Zijlstra
2019-02-27 17:38 ` Linus Torvalds
2019-02-27 17:57 ` Nadav Amit
2019-02-27 18:55 ` Nadav Amit
2019-02-27 19:41 ` Linus Torvalds
2019-03-08 13:35 ` Peter Zijlstra
2019-02-27 10:12 ` [PATCH 2/5] x86/percpu: Relax smp_processor_id() Peter Zijlstra
2019-02-27 10:12 ` [PATCH 3/5] x86/percpu, x86/irq: Relax {set,get}_irq_regs() Peter Zijlstra
2019-02-27 10:12 ` [PATCH 4/5] x86/percpu, x86/tlb: Relax cpu_tlbstate accesses Peter Zijlstra
2019-02-27 10:12 ` [PATCH 5/5] x86/percpu, sched/fair: Avoid local_clock() Peter Zijlstra
2019-02-27 10:24 ` [PATCH 6/5] x86/percpu: Optimize raw_cpu_xchg() Peter Zijlstra
2019-02-27 14:43 ` Peter Zijlstra
2019-02-27 23:16 ` [PATCH 0/5] x86/percpu semantics and fixes Nadav Amit
2019-03-08 14:50 ` Peter Zijlstra
2019-03-08 19:35 ` Nadav Amit
2019-03-08 20:56 ` Peter Zijlstra
2019-03-10 12:46 ` Peter Zijlstra [this message]
2019-03-08 22:48 ` Peter Zijlstra
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