Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765946AbXEVOer (ORCPT ); Tue, 22 May 2007 10:34:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757473AbXEVOeh (ORCPT ); Tue, 22 May 2007 10:34:37 -0400 Received: from e6.ny.us.ibm.com ([32.97.182.146]:40216 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756504AbXEVOeg (ORCPT ); Tue, 22 May 2007 10:34:36 -0400 Date: Tue, 22 May 2007 07:34:32 -0700 From: Nishanth Aravamudan To: Steve Fox Cc: Badari Pulavarty , Anton Blanchard , Hugh Dickins , Christoph Lameter , Andrew Morton , netdev@vger.kernel.org, lkml , sfr@canb.auug.org.au, ak@suse.de, Andy Whitcroft Subject: Re: select(0, ..) is valid ? Message-ID: <20070522143432.GA1938@us.ibm.com> References: <1179250159.2836.117.camel@dyn9047017100.beaverton.ibm.com> <20070515104453.f901e91f.akpm@linux-foundation.org> <20070516153703.GA26912@kryten> <1179363553.16195.10.camel@dyn9047017100.beaverton.ibm.com> <1179843397.3124.109.camel@drfickle.rchland.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1179843397.3124.109.camel@drfickle.rchland.ibm.com> X-Operating-System: Linux 2.6.21-cfs-v9-dirty (x86_64) User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2790 Lines: 91 On 22.05.2007 [09:16:37 -0500], Steve Fox wrote: > On Wed, 2007-05-16 at 17:59 -0700, Badari Pulavarty wrote: > > > Here it is .. > > > > Should I do one for poll() also ? > > > > Thanks, > > Badari > > > > Optimize select by a using stack space for small fd sets. > > core_sys_select() already has this optimization. This is > > for compat version. > > > > Signed-off-by: Badari Pulavarty > > --- > > fs/compat.c | 17 +++++++++++------ > > 1 file changed, 11 insertions(+), 6 deletions(-) > > > > Index: linux-2.6.22-rc1/fs/compat.c > > =================================================================== > > --- linux-2.6.22-rc1.orig/fs/compat.c 2007-05-12 18:45:56.000000000 -0700 > > +++ linux-2.6.22-rc1/fs/compat.c 2007-05-16 17:50:39.000000000 -0700 > > @@ -1544,9 +1544,10 @@ int compat_core_sys_select(int n, compat > > compat_ulong_t __user *outp, compat_ulong_t __user *exp, s64 *timeout) > > { > > fd_set_bits fds; > > - char *bits; > > + void *bits; > > int size, max_fds, ret = -EINVAL; > > struct fdtable *fdt; > > + long stack_fds[SELECT_STACK_ALLOC/sizeof(long)]; > > > > if (n < 0) > > goto out_nofds; > > @@ -1564,11 +1565,14 @@ int compat_core_sys_select(int n, compat > > * since we used fdset we need to allocate memory in units of > > * long-words. > > */ > > - ret = -ENOMEM; > > size = FDS_BYTES(n); > > - bits = kmalloc(6 * size, GFP_KERNEL); > > - if (!bits) > > - goto out_nofds; > > + bits = stack_fds; > > + if (size > sizeof(stack_fds) / 6) { > > + bits = kmalloc(6 * size, GFP_KERNEL); > > + ret = -ENOMEM; > > + if (!bits) > > + goto out_nofds; > > + } > > fds.in = (unsigned long *) bits; > > fds.out = (unsigned long *) (bits + size); > > fds.ex = (unsigned long *) (bits + 2*size); > > @@ -1600,7 +1604,8 @@ int compat_core_sys_select(int n, compat > > compat_set_fd_set(n, exp, fds.res_ex)) > > ret = -EFAULT; > > out: > > - kfree(bits); > > + if (bits != stack_fds) > > + kfree(bits); > > out_nofds: > > return ret; > > } > > Andy put this through a couple machines on test.kernel.org and elm3b6 > was fixed, however elm3b239 still had a boot error. > > BUG: at mm/slab.c:777 __find_general_cachep() > > Call Trace: > [] __kmalloc+0xa6/0xe0 > [] cache_k8_northbridges+0x9b/0x120 I believe this is fixed by: http://lkml.org/lkml/2007/5/18/19 Care to stack it on top and retest? Thanks, Nish -- Nishanth Aravamudan IBM Linux Technology Center - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/