From: Valentin Schneider <vschneid@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <frederic@kernel.org>,
Yair Podemsky <ypodemsk@redhat.com>,
linux@armlinux.org.uk, mpe@ellerman.id.au, npiggin@gmail.com,
christophe.leroy@csgroup.eu, hca@linux.ibm.com,
gor@linux.ibm.com, agordeev@linux.ibm.com,
borntraeger@linux.ibm.com, svens@linux.ibm.com,
davem@davemloft.net, tglx@linutronix.de, mingo@redhat.com,
bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org,
hpa@zytor.com, will@kernel.org, aneesh.kumar@linux.ibm.com,
akpm@linux-foundation.org, arnd@arndb.de, keescook@chromium.org,
paulmck@kernel.org, jpoimboe@kernel.org, samitolvanen@google.com,
ardb@kernel.org, juerg.haefliger@canonical.com,
rmk+kernel@armlinux.org.uk, geert+renesas@glider.be,
tony@atomide.com, linus.walleij@linaro.org,
sebastian.reichel@collabora.com, nick.hawkins@hpe.com,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org,
sparclinux@vger.kernel.org, linux-arch@vger.kernel.org,
linux-mm@kvack.org, mtosatti@redhat.com, dhildenb@redhat.com,
alougovs@redhat.com
Subject: Re: [PATCH 3/3] mm/mmu_gather: send tlb_remove_table_smp_sync IPI only to CPUs in kernel mode
Date: Thu, 06 Apr 2023 15:11:52 +0100 [thread overview]
Message-ID: <xhsmh8rf59k2f.mognet@vschneid.remote.csb> (raw)
In-Reply-To: <20230406133805.GO386572@hirez.programming.kicks-ass.net>
On 06/04/23 15:38, Peter Zijlstra wrote:
> On Wed, Apr 05, 2023 at 01:45:02PM +0100, Valentin Schneider wrote:
>>
>> I've been hacking on something like this (CSD deferral for NOHZ-full),
>> and unfortunately this uses the CPU-local cfd_data storage thing, which
>> means any further smp_call_function() from the same CPU to the same
>> destination will spin on csd_lock_wait(), waiting for the target CPU to
>> come out of userspace and flush the queue - and we've just spent extra
>> effort into *not* disturbing it, so that'll take a while :(
>
> I'm not sure I buy into deferring stuff.. a NOHZ_FULL cpu might 'never'
> come back. Queueing data just in case it does seems wasteful.
Putting those callbacks straight into the bin would make my life much
easier!
Unfortunately, even if they really should, I don't believe all of the
things being crammed onto NOHZ_FULL CPUs have the same definition of
'never' as we do :/
next prev parent reply other threads:[~2023-04-06 14:12 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-04 13:42 [PATCH 0/3] send tlb_remove_table_smp_sync IPI only to necessary CPUs Yair Podemsky
2023-04-04 13:42 ` [PATCH 1/3] arch: Introduce ARCH_HAS_CPUMASK_BITS Yair Podemsky
2023-04-04 13:47 ` David Hildenbrand
2023-04-04 13:42 ` [PATCH 2/3] mm/mmu_gather: send tlb_remove_table_smp_sync IPI only to MM CPUs Yair Podemsky
2023-04-04 14:57 ` Peter Zijlstra
2023-04-04 13:42 ` [PATCH 3/3] mm/mmu_gather: send tlb_remove_table_smp_sync IPI only to CPUs in kernel mode Yair Podemsky
2023-04-04 14:03 ` David Hildenbrand
2023-04-04 15:12 ` Peter Zijlstra
2023-04-04 16:00 ` Peter Zijlstra
2023-04-05 0:53 ` Hillf Danton
2023-04-05 10:43 ` Frederic Weisbecker
2023-04-05 11:10 ` Frederic Weisbecker
2023-04-05 11:41 ` Peter Zijlstra
2023-04-05 12:00 ` David Hildenbrand
2023-04-05 12:05 ` Frederic Weisbecker
2023-04-05 12:31 ` Frederic Weisbecker
2023-04-05 12:45 ` Valentin Schneider
2023-04-06 13:38 ` Peter Zijlstra
2023-04-06 14:11 ` Valentin Schneider [this message]
2023-04-06 14:39 ` Peter Zijlstra
2023-04-05 19:45 ` Marcelo Tosatti
2023-04-05 19:52 ` Peter Zijlstra
2023-04-06 12:38 ` Marcelo Tosatti
2023-04-06 13:29 ` Peter Zijlstra
2023-04-06 14:04 ` Peter Zijlstra
2023-04-06 14:42 ` David Hildenbrand
2023-04-06 15:06 ` Peter Zijlstra
2023-04-06 15:02 ` Peter Zijlstra
2023-04-06 15:51 ` David Hildenbrand
2023-04-06 18:27 ` Peter Zijlstra
2023-04-19 11:30 ` David Hildenbrand
2023-04-19 11:39 ` Marcelo Tosatti
2023-04-05 19:43 ` Marcelo Tosatti
2023-04-05 19:54 ` Peter Zijlstra
2023-04-06 12:49 ` Marcelo Tosatti
2023-04-06 13:32 ` Peter Zijlstra
2023-04-19 11:01 ` Marcelo Tosatti
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