linux-kernel - Re: More than 1M open file descriptors

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Date:	Wed, 19 May 2010 18:36:05 +0300
From:	Felipe Balbi <felipe.balbi@...ia.com>
To:	ext John Masinter <johnmasinter@...il.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: More than 1M open file descriptors

On Wed, May 19, 2010 at 04:52:56PM +0200, ext John Masinter wrote:
>I'm a software engineer and work with a fortune-500 company. We have a
>line of linux-powered network security appliances and I am responsible
>for Linux / OS development.
>Our multi-core appliance handles a large number of low-bandwith tcp
>connections, and after years of performance streamlining, we have hit
>the kernel's million tcp connection limit.
>Is there a kernel hack to increase the file descriptor limit beyond 1M
>to that we may have more than 1M open tcp connections? If this is
>discussed elsewhere, please point me in the right direction. Many
>thanks to everyone that contributes to open source.

look into fs/file.c
increasing sysctl_nr_open like below should help:

diff --git a/fs/file.c b/fs/file.c
index 87e1290..23c83df 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -27,9 +27,9 @@ struct fdtable_defer {
  	struct fdtable *next;
  };
  
-int sysctl_nr_open __read_mostly = 1024*1024;
+int sysctl_nr_open __read_mostly = 4*1024*1024;
  int sysctl_nr_open_min = BITS_PER_LONG;
-int sysctl_nr_open_max = 1024 * 1024; /* raised later */
+int sysctl_nr_open_max = 4 * 1024 * 1024; /* raised later */
  
  /*
   * We use this list to defer free fdtables that have vmalloced

you can also do it via /proc AFAICT.

-- 
balbi

DefectiveByDesign.org
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