linux-kernel - [RFC][PATCH 11/11] optimize c/r check in dup

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Message-Id: <20090305163913.E59C59BB@kernel>
Date:	Thu, 05 Mar 2009 08:39:13 -0800
From:	Dave Hansen <dave@...ux.vnet.ibm.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	containers <containers@...ts.linux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Serge E. Hallyn" <serue@...ibm.com>,
	Oren Laadan <orenl@...columbia.edu>,
	Alexey Dobriyan <adobriyan@...il.com>,
	Christoph Hellwig <hch@...radead.org>,
	Dave Hansen <dave@...ux.vnet.ibm.com>
Subject: [RFC][PATCH 11/11] optimize c/r check in dup_fd()


__scan_files_for_cr() should compile down to nothing
if checkpoint/restart is disabled.

But, I think the spinlocks in fcheck_files() keep
the compiler from figuring this out.  So, instead
if putting in some #ifdefs, use our new cr_enabled()
helper.

I've verified that this puts .text size back to
where it was without the __scan_files_for_cr() call.

Signed-off-by: Dave Hansen <dave@...ux.vnet.ibm.com>
---

 linux-2.6.git-dave/fs/file.c |    3 +++
 1 file changed, 3 insertions(+)

diff -puN fs/file.c~optimize-cr-checkk fs/file.c
--- linux-2.6.git/fs/file.c~optimize-cr-checkk	2009-03-05 08:37:05.000000000 -0800
+++ linux-2.6.git-dave/fs/file.c	2009-03-05 08:37:05.000000000 -0800
@@ -290,6 +290,9 @@ static void __scan_files_for_cr(struct f
 {
 	int i;
 
+	if (!cr_enabled())
+		return;
+
 	for (i = 0; i < files->fdtab.max_fds; i++) {
 		struct file *f = fcheck_files(files, i);
 		if (!f)
_
--
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