From: Dave Hansen <haveblue@us.ibm.com>
To: schwidefsky@de.ibm.com
Cc: linux-kernel@vger.kernel.org, virtualization@lists.osdl.org,
akpm@osdl.org, nickpiggin@yahoo.com.au, frankeh@watson.ibm.com,
rhim@cc.gateh.edu
Subject: Re: [patch 4/9] Guest page hinting: volatile swap cache.
Date: Fri, 01 Sep 2006 08:52:19 -0700 [thread overview]
Message-ID: <1157125939.28577.100.camel@localhost.localdomain> (raw)
In-Reply-To: <1157125031.21733.21.camel@localhost>
On Fri, 2006-09-01 at 17:37 +0200, Martin Schwidefsky wrote:
> On Fri, 2006-09-01 at 08:04 -0700, Dave Hansen wrote:
> > > +EXPORT_SYMBOL(find_get_page_nodiscard);
> > > +
> > > +#endif
> >
> > Is it worth having another full copy of find_get_page()? What about a
> > "nodiscard" argument?
>
> That is a hard call to make. I really tried hard to avoid adding any
> overhead to a system running without the feature.
The overhead being the extra (potentially unused) argument to the
function? Plus, that the function isn't inlined and thus will be unable
to have its argument optimized away?
In the worse case, we're talking about the cost of saving and restoring
the contents of a single register to the stack. In other arches, we're
talking about the push of an immediate on the stack for the call.
Yeah, it is a hard call to make, especially if you're aiming for
zero-impact.
-- Dave
prev parent reply other threads:[~2006-09-01 15:52 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-09-01 11:10 [patch 4/9] Guest page hinting: volatile swap cache Martin Schwidefsky
2006-09-01 14:58 ` Dave Hansen
2006-09-01 15:33 ` Martin Schwidefsky
2006-09-01 15:04 ` Dave Hansen
2006-09-01 15:37 ` Martin Schwidefsky
2006-09-01 15:52 ` Dave Hansen [this message]
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=1157125939.28577.100.camel@localhost.localdomain \
--to=haveblue@us.ibm.com \
--cc=akpm@osdl.org \
--cc=frankeh@watson.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=nickpiggin@yahoo.com.au \
--cc=rhim@cc.gateh.edu \
--cc=schwidefsky@de.ibm.com \
--cc=virtualization@lists.osdl.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).