Re: inode_lock heavily contended in 2.6.11
From: Andrew Morton
Date: Mon Mar 14 2005 - 00:16:49 EST
Peter Chubb <peterc@xxxxxxxxxxxxxxxxxx> wrote:
> When running reaim7 on a 12-way IA64 on an ext2 filesystem on a ram
> disc, I see very heavy contention on inode_lock.
Yes, that's a big global lock, protecting global resources. I always
expected it to hit someone's fan, but it never did.
> lockstat output shows:
> SPINLOCKS HOLD WAIT
> UTIL CON MEAN( MAX ) MEAN( MAX )(% CPU) TOTAL NOWAIT SPIN RJECT NAME
> 46.8% 52.4% 1.9us( 130us) 20us(8073us)(21.5%) 5072151 47.6% 52.4% 0% inode_lock
> 15.9% 59.5% 3.8us( 61us) 18us(7067us)( 3.9%) 852983 40.5% 59.5% 0% __sync_single_inode+0xf0
> 9.2% 59.0% 1.2us( 25us) 20us(8073us)( 7.8%) 1596487 41.0% 59.0% 0% generic_osync_inode+0xe0
> Is anyone else seeing this on more realistic workloads?
An fsync/O_SYNC-intensive workload on a ram disk is likely to bring it out,
yes. But once one has real disks under there, the acquisition frequency
will fall a lot.
Unless people are being all shy again, I don't think anyone has hit
significant inode_lock problems on more real-world things.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/