From: Marcelo Tosatti <mtosatti@redhat.com>
To: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Cc: avi@redhat.com, kvm@vger.kernel.org
Subject: Re: [PATCH] KVM: x86: lapic: Fix the misuse of likely() in find_highest_vector()
Date: Mon, 27 Aug 2012 17:25:42 -0300 [thread overview]
Message-ID: <20120827202542.GA1414@amt.cnet> (raw)
In-Reply-To: <20120824181549.e1535ae0.yoshikawa.takuya@oss.ntt.co.jp>
On Fri, Aug 24, 2012 at 06:15:49PM +0900, Takuya Yoshikawa wrote:
> Although returning -1 should be likely according to the likely(),
> the ASSERT in apic_find_highest_irr() will be triggered in such a case.
> It seems that this optimization is not working as expected.
>
> This patch simplifies the logic to mitigate this issue: search for the
> first non-zero word in a for loop and then use __fls() if found. When
> nothing found, we are out of the loop, so we can just return -1.
Numbers please?
> Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
> ---
> arch/x86/kvm/lapic.c | 18 ++++++++++--------
> 1 files changed, 10 insertions(+), 8 deletions(-)
next prev parent reply other threads:[~2012-08-27 20:54 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-24 9:15 [PATCH] KVM: x86: lapic: Fix the misuse of likely() in find_highest_vector() Takuya Yoshikawa
2012-08-27 20:25 ` Marcelo Tosatti [this message]
2012-08-28 9:57 ` Takuya Yoshikawa
2012-08-29 19:10 ` Marcelo Tosatti
2012-08-29 22:51 ` Michael S. Tsirkin
2012-08-30 1:09 ` Takuya Yoshikawa
2012-08-30 6:37 ` Michael S. Tsirkin
2012-08-30 9:50 ` Takuya Yoshikawa
2012-08-30 10:10 ` Michael S. Tsirkin
2012-08-30 10:24 ` Takuya Yoshikawa
2012-08-30 10:44 ` Michael S. Tsirkin
2012-08-30 12:30 ` [PATCH -v3] KVM: x86: lapic: Clean up find_highest_vector() and count_vectors() Takuya Yoshikawa
2012-08-30 13:21 ` Michael S. Tsirkin
2012-08-30 16:09 ` Takuya Yoshikawa
2012-08-30 16:49 ` Michael S. Tsirkin
2012-09-05 8:30 ` Takuya Yoshikawa
2012-09-05 9:26 ` Michael S. Tsirkin
2012-09-05 9:40 ` Takuya Yoshikawa
2012-09-05 9:51 ` Michael S. Tsirkin
2012-09-05 10:30 ` [PATCH -v4] " Takuya Yoshikawa
2012-09-05 10:58 ` Michael S. Tsirkin
2012-09-12 16:39 ` Marcelo Tosatti
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120827202542.GA1414@amt.cnet \
--to=mtosatti@redhat.com \
--cc=avi@redhat.com \
--cc=kvm@vger.kernel.org \
--cc=yoshikawa.takuya@oss.ntt.co.jp \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.