Re: [rfc][patch] store-free path walking

[David Miller]

From: Nick Piggin <npiggin@xxxxxxx>
Date: Fri, 9 Oct 2009 05:50:50 +0200

> OK, I got rid of this guy from the RCU walk. Basically now hold
> vfsmount_lock over the entire RCU path walk (which also pins the mnt)
> and use a seqlock in the fs struct to get a consistent mnt,dentry
> pair. This also simplifies the walk because we don't need the
> complexity to avoid mntget/mntput (just do one final mntget on the
> resulting mnt before dropping vfsmount_lock).
> 
> vfsmount_lock adds one per-cpu atomic for the spinlock, and we
> remove two thread-shared atomics for fs->lock so a net win for
> both single threaded performance and thread-shared scalability.
> Latency is no problem because we hold rcu_read_lock for the same
> length of time anyway.
> 
> The parallel git diff workload is improved by serveral percent.

Sounds sweet Nick, can't wait to play with your next set of
patches here.
--
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/