From: Peter Zijlstra <peterz@infradead.org>
To: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
"Steven Rostedt (VMware)" <rostedt@goodmis.org>,
Jiri Kosina <jkosina@suse.cz>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Chris von Recklinghausen <crecklin@redhat.com>,
Jason Baron <jbaron@akamai.com>, Scott Wood <swood@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
Clark Williams <williams@redhat.com>,
x86@kernel.org
Subject: Re: [PATCH V6 4/6] x86/alternative: Batch of patch operations
Date: Wed, 12 Jun 2019 16:52:13 +0200 [thread overview]
Message-ID: <20190612145213.GK3436@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <ca506ed52584c80f64de23f6f55ca288e5d079de.1560325897.git.bristot@redhat.com>
On Wed, Jun 12, 2019 at 11:57:29AM +0200, Daniel Bristot de Oliveira wrote:
> When a static key has more than one entry, these steps are called once for
> each entry. The number of IPIs then is linear with regard to the number 'n' of
> entries of a key: O(n*3), which is O(n).
> Doing the update in this way, the number of IPI becomes O(3) with regard
> to the number of keys, which is O(1).
That's not quite true, what you're doing is n/X, which, in the end, is
still O(n).
It just so happens your X is 128, and so any n smaller than that ends up
being 1.
next prev parent reply other threads:[~2019-06-12 14:53 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-12 9:57 [PATCH V6 0/6] x86/jump_label: Bound IPIs sent when updating a static key Daniel Bristot de Oliveira
2019-06-12 9:57 ` [PATCH V6 1/6] jump_label: Add a jump_label_can_update() helper Daniel Bristot de Oliveira
2019-06-17 14:13 ` [tip:locking/core] " tip-bot for Daniel Bristot de Oliveira
2019-06-12 9:57 ` [PATCH V6 2/6] x86/jump_label: Add a __jump_label_set_jump_code() helper Daniel Bristot de Oliveira
2019-06-17 14:13 ` [tip:locking/core] " tip-bot for Daniel Bristot de Oliveira
2019-06-12 9:57 ` [PATCH V6 3/6] jump_label: Sort entries of the same key by the code Daniel Bristot de Oliveira
2019-06-17 14:14 ` [tip:locking/core] " tip-bot for Daniel Bristot de Oliveira
2019-06-12 9:57 ` [PATCH V6 4/6] x86/alternative: Batch of patch operations Daniel Bristot de Oliveira
2019-06-12 14:52 ` Peter Zijlstra [this message]
2019-06-12 16:33 ` Daniel Bristot de Oliveira
2019-06-17 14:15 ` [tip:locking/core] " tip-bot for Daniel Bristot de Oliveira
2019-06-12 9:57 ` [PATCH V6 5/6] jump_label: Batch updates if arch supports it Daniel Bristot de Oliveira
2019-06-17 14:15 ` [tip:locking/core] " tip-bot for Daniel Bristot de Oliveira
2019-06-12 9:57 ` [PATCH V6 6/6] x86/jump_label: Batch jump label updates Daniel Bristot de Oliveira
2019-06-17 14:16 ` [tip:locking/core] " tip-bot for Daniel Bristot de Oliveira
2019-06-12 17:07 ` [PATCH V6 0/6] x86/jump_label: Bound IPIs sent when updating a static key Peter Zijlstra
2019-06-13 8:08 ` Daniel Bristot de Oliveira
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