Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759706Ab3ICHYJ (ORCPT ); Tue, 3 Sep 2013 03:24:09 -0400 Received: from mail-wi0-f177.google.com ([209.85.212.177]:48902 "EHLO mail-wi0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759470Ab3ICHYH (ORCPT ); Tue, 3 Sep 2013 03:24:07 -0400 MIME-Version: 1.0 Reply-To: sedat.dilek@gmail.com In-Reply-To: <20130903060130.GD16261@gmail.com> References: <5220F090.5050908@hp.com> <20130830194059.GC13318@ZenIV.linux.org.uk> <5220F811.9060902@hp.com> <20130830202608.GD13318@ZenIV.linux.org.uk> <52210225.60805@hp.com> <20130830204852.GE13318@ZenIV.linux.org.uk> <52214EBC.90100@hp.com> <20130831023516.GI13318@ZenIV.linux.org.uk> <20130831024233.GJ13318@ZenIV.linux.org.uk> <5224E647.80303@hp.com> <20130903060130.GD16261@gmail.com> Date: Tue, 3 Sep 2013 09:24:06 +0200 Message-ID: Subject: Re: [PATCH v7 1/4] spinlock: A new lockref structure for lockless update of refcount From: Sedat Dilek To: Ingo Molnar Cc: Waiman Long , Al Viro , Linus Torvalds , Benjamin Herrenschmidt , Jeff Layton , Miklos Szeredi , Ingo Molnar , Thomas Gleixner , linux-fsdevel , Linux Kernel Mailing List , Peter Zijlstra , Steven Rostedt , Andi Kleen , "Chandramouleeswaran, Aswin" , "Norton, Scott J" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2894 Lines: 73 On Tue, Sep 3, 2013 at 8:01 AM, Ingo Molnar wrote: > > * Waiman Long wrote: > >> On 08/30/2013 10:42 PM, Al Viro wrote: >> >On Sat, Aug 31, 2013 at 03:35:16AM +0100, Al Viro wrote: >> > >> >>Aha... OK, I see what's going on. We end up with shm_mnt *not* marked >> >>as long-living vfsmount, even though it lives forever. See if the >> >>following helps; if it does (and I very much expect it to), we want to >> >>put it in -stable. As it is, you get slow path in mntput() each time >> >>a file created by shmem_file_setup() gets closed. For no reason whatsoever... >> >We still want MS_NOUSER on shm_mnt, so we'd better make sure that >> >shmem_fill_super() sets it on the internal instance... Fixed variant >> >follows: >> > >> >Signed-off-by: Al Viro >> >diff --git a/mm/shmem.c b/mm/shmem.c >> >index e43dc55..5261498 100644 >> >--- a/mm/shmem.c >> >+++ b/mm/shmem.c >> >@@ -2615,13 +2615,15 @@ int shmem_fill_super(struct super_block *sb, void *data, int silent) >> > * tmpfs instance, limiting inodes to one per page of lowmem; >> > * but the internal instance is left unlimited. >> > */ >> >- if (!(sb->s_flags& MS_NOUSER)) { >> >+ if (!(sb->s_flags& MS_KERNMOUNT)) { >> > sbinfo->max_blocks = shmem_default_max_blocks(); >> > sbinfo->max_inodes = shmem_default_max_inodes(); >> > if (shmem_parse_options(data, sbinfo, false)) { >> > err = -EINVAL; >> > goto failed; >> > } >> >+ } else { >> >+ sb->s_flags |= MS_NOUSER; >> > } >> > sb->s_export_op =&shmem_export_ops; >> > sb->s_flags |= MS_NOSEC; >> >@@ -2831,8 +2833,7 @@ int __init shmem_init(void) >> > goto out2; >> > } >> > >> >- shm_mnt = vfs_kern_mount(&shmem_fs_type, MS_NOUSER, >> >- shmem_fs_type.name, NULL); >> >+ shm_mnt = kern_mount(&shmem_fs_type); >> > if (IS_ERR(shm_mnt)) { >> > error = PTR_ERR(shm_mnt); >> > printk(KERN_ERR "Could not kern_mount tmpfs\n"); >> >> Yes, that patch worked. It eliminated the lglock as a bottleneck in >> the AIM7 workload. The lg_global_lock did not show up in the perf >> profile, whereas the lg_local_lock was only 0.07%. > > Just curious: what's the worst bottleneck now in the optimized kernel? :-) > > Thanks, > > Ingo Can someone summarize this thread (70+ postings)? Which patches are needed? And fixing what? ( Can people provide separate patches with a proper changelog? ) Improvements? Thanks. - Sedat (still struggling with perf) - -- 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/