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From: Herbert Xu <herbert@gondor.apana.org.au>
To: Andy Lutomirski <luto@amacapital.net>
Cc: mingo@kernel.org, brgerst@gmail.com,
	torvalds@linux-foundation.org, x86@kernel.org,
	linux-kernel@vger.kernel.org, hpa@zytor.com, dvlasenk@redhat.com,
	bp@suse.de, tglx@linutronix.de, jpoimboe@redhat.com
Subject: Re: [PATCH v3 0/7] x86: Rewrite switch_to()
Date: Wed, 17 Aug 2016 13:16:50 +0800	[thread overview]
Message-ID: <20160817051650.GA1581@gondor.apana.org.au> (raw)
In-Reply-To: <CALCETrX_uUhv-BwmHfgZRCZbBtjKzBz-LZykOLAKM=TV1R8jog@mail.gmail.com>

Andy Lutomirski <luto@amacapital.net> wrote:
>
> I will be quite surprised if you can measure any effect at all.  I've
> never seen context switches take fewer than ~2k cycles, and on my
> laptop, they take 8k-9k cycles.  The scheduler is really, really slow.

Indeed, I think I still have a bugzilla entry somewhere regarding
the huge performance regression when we first switched over to the
current scheduler.

Over the years people have been trying to hack around it, e.g.,
network driver polling, low latency socket, anything to avoid
going into the scheduler.  We really should fix it properly some
day.

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

  reply	other threads:[~2016-08-17  5:17 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-13 16:38 [PATCH v3 0/7] x86: Rewrite switch_to() Brian Gerst
2016-08-13 16:38 ` [PATCH v3 1/7] x86-32, kgdb: Don't use thread.ip in sleeping_thread_to_gdb_regs() Brian Gerst
2016-08-24 13:07   ` [tip:x86/asm] sched/x86/32, " tip-bot for Brian Gerst
2016-08-13 16:38 ` [PATCH v3 2/7] x86-64, kgdb: clear GDB_PS on 64-bit Brian Gerst
2016-08-24 13:07   ` [tip:x86/asm] sched/x86/64, kgdb: Clear " tip-bot for Brian Gerst
2016-08-13 16:38 ` [PATCH v3 3/7] x86: Add struct inactive_task_frame Brian Gerst
2016-08-24 13:08   ` [tip:x86/asm] sched/x86: Add 'struct inactive_task_frame' to better document the sleeping task stack frame tip-bot for Brian Gerst
2016-08-13 16:38 ` [PATCH v3 4/7] x86: Rewrite switch_to() code Brian Gerst
2016-08-24 13:08   ` [tip:x86/asm] sched/x86: Rewrite the " tip-bot for Brian Gerst
2016-08-13 16:38 ` [PATCH v3 5/7] x86: Pass kernel thread parameters in fork_frame Brian Gerst
2016-08-24 13:09   ` [tip:x86/asm] sched/x86: Pass kernel thread parameters in 'struct fork_frame' tip-bot for Brian Gerst
2016-08-13 16:38 ` [PATCH v3 6/7] x86: Fix thread_saved_pc() Brian Gerst
2016-08-24 13:09   ` [tip:x86/asm] sched/x86: " tip-bot for Brian Gerst
2016-08-13 16:38 ` [PATCH v3 7/7] Revert "sched: Mark __schedule() stack frame as non-standard" Brian Gerst
2016-08-24 13:09   ` [tip:x86/asm] sched: Remove __schedule() non-standard frame annotation tip-bot for Brian Gerst
2016-08-13 17:16 ` [PATCH v3 0/7] x86: Rewrite switch_to() Linus Torvalds
2016-08-13 18:15   ` Brian Gerst
2016-08-13 18:45     ` Ingo Molnar
2016-08-13 19:33       ` Andy Lutomirski
2016-08-17  5:16         ` Herbert Xu [this message]
2016-08-14 14:18       ` Brian Gerst
2016-08-15  5:10         ` Ingo Molnar
2016-08-15 11:43           ` Brian Gerst
2016-08-17 21:23           ` Andy Lutomirski
2016-08-17 21:20 ` Josh Poimboeuf

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