Re: [PATCH V2] Raise default hard ulimit on number of files to 4096

[Tim Gardner <tim.gardner@canonical.com>]

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On 03/31/2011 03:35 PM, Andrew Morton wrote:
>
> ^^ how not to write a changelog.
>

It seemed like plagiarism to just copy Dan's argument, but now here you 
have it.

rtg
-- 
Tim Gardner tim.gardner@canonical.com

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>From 819066637c964290fbab058b578dadbb31ae4235 Mon Sep 17 00:00:00 2001
From: Tim Gardner <tim.gardner@canonical.com>
Date: Thu, 31 Mar 2011 15:07:48 -0600
Subject: [PATCH] Raise default hard ulimit on number of files to 4096

Apps are increasingly using more than 1024 file descriptors.
See discussion in several distro bug trackers, e.g.
BugLink: http://bugs.launchpad.net/bugs/663090
https://issues.rpath.com/browse/RPL-2054

You don't want to raise the default soft limit, since that might break
apps that use select(), but it's safe to raise the default hard limit;
that way, apps that know they need lots of file descriptors can raise their
soft limit without needing root, and without user intervention.

Ubuntu is doing this with a kernel change because they have a policy
of not changing kernel defaults in userland.

While 4096 might not be enough for *all* apps, it seems to be plenty
for the apps I've seen lately that are unhappy with 1024.

Cc: Dan Kegel <dank@kegel.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
---
 include/asm-generic/resource.h |    2 +-
 include/linux/fs.h             |    3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/asm-generic/resource.h b/include/asm-generic/resource.h
index 587566f..61fa862 100644
--- a/include/asm-generic/resource.h
+++ b/include/asm-generic/resource.h
@@ -78,7 +78,7 @@
 	[RLIMIT_CORE]		= {              0,  RLIM_INFINITY },	\
 	[RLIMIT_RSS]		= {  RLIM_INFINITY,  RLIM_INFINITY },	\
 	[RLIMIT_NPROC]		= {              0,              0 },	\
-	[RLIMIT_NOFILE]		= {       INR_OPEN,       INR_OPEN },	\
+	[RLIMIT_NOFILE]		= {   INR_OPEN_CUR,   INR_OPEN_MAX },	\
 	[RLIMIT_MEMLOCK]	= {    MLOCK_LIMIT,    MLOCK_LIMIT },	\
 	[RLIMIT_AS]		= {  RLIM_INFINITY,  RLIM_INFINITY },	\
 	[RLIMIT_LOCKS]		= {  RLIM_INFINITY,  RLIM_INFINITY },	\
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 52f283c..6e1e4e6 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -23,7 +23,8 @@
 
 /* Fixed constants first: */
 #undef NR_OPEN
-#define INR_OPEN 1024		/* Initial setting for nfile rlimits */
+#define INR_OPEN_CUR 1024	/* Initial setting for nfile rlimits */
+#define INR_OPEN_MAX 4096	/* Hard limit for nfile rlimits */
 
 #define BLOCK_SIZE_BITS 10
 #define BLOCK_SIZE (1<<BLOCK_SIZE_BITS)
-- 
1.7.0.4