From: Keir Fraser <keir.fraser@eu.citrix.com>
To: Juergen Gross <juergen.gross@fujitsu-siemens.com>,
xen-devel@lists.xensource.com
Subject: Re: Patch: implementing least priority interrupt routing
Date: Tue, 18 Nov 2008 10:18:18 +0000 [thread overview]
Message-ID: <C54846EA.1F52A%keir.fraser@eu.citrix.com> (raw)
In-Reply-To: <C5484527.1F525%keir.fraser@eu.citrix.com>
On 18/11/08 10:10, "Keir Fraser" <keir.fraser@eu.citrix.com> wrote:
> Where idle means 'not processing an interrupt'. Which ought to be by far the
> most common case even for a non-idle CPU. Does this really improve load
> balancing all that much? Does BS2000 spend lots of time in IRQ context?
>
> My fear is that extra complexity here slows down dest_lowprio for all OSes
> (and it's used by a lot of OSes) for every ExtInt delivered.
That fear is probably unfounded actually, given we scan a vcpu's IRR bitmap
on *every* vmentry currently. Still it would be nice to know the motivation
behind this patch (beyond 'it's nice to behave like native hardware'). We
might still find a cheaper method with similar or better benefit (e.g.,
check vcpu_runnable() to find idle VCPUs is cheaper and may be more
accurate).
-- Keir
next prev parent reply other threads:[~2008-11-18 10:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-11-18 9:59 Patch: implementing least priority interrupt routing Juergen Gross
2008-11-18 10:10 ` Keir Fraser
2008-11-18 10:18 ` Keir Fraser [this message]
2008-11-18 10:37 ` Juergen Gross
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=C54846EA.1F52A%keir.fraser@eu.citrix.com \
--to=keir.fraser@eu.citrix.com \
--cc=juergen.gross@fujitsu-siemens.com \
--cc=xen-devel@lists.xensource.com \
/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.