linux-kernel - Re: [RESEND PATCH v7 0/4] vfs: Use per-cpu list for SB's s

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Message-ID: <575720A6.4000700@hpe.com>
Date:	Tue, 7 Jun 2016 15:29:42 -0400
From:	Waiman Long <waiman.long@....com>
To:	Waiman Long <Waiman.Long@....com>
CC:	Alexander Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.com>,
	Jeff Layton <jlayton@...chiereds.net>,
	"J. Bruce Fields" <bfields@...ldses.org>,
	Tejun Heo <tj@...nel.org>,
	Christoph Lameter <cl@...ux-foundation.org>,
	<linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Andi Kleen <andi@...stfloor.org>,
	Dave Chinner <dchinner@...hat.com>,
	Boqun Feng <boqun.feng@...il.com>,
	Scott J Norton <scott.norton@....com>,
	Douglas Hatch <doug.hatch@....com>
Subject: Re: [RESEND PATCH v7 0/4] vfs: Use per-cpu list for SB's s_inodes
 list

On 06/07/2016 03:24 PM, Waiman Long wrote:
> v6->v7:
>   - Fix the race condition in __pcpu_list_next_cpu() as reported by
>     Jan Kara.
>   - No changes in patches 2-4.
>
> v5->v6:
>   - Remove patch 5 which can increase the kernel testing matrix.
>   - Disable preemption in pcpu_list_add() as it was complained by
>     the 0-day test even though it is not technically necessary.
>   - Add a PERCPU_LIST_WARN_ON() macro to simplify code.
>   - No changes in patches 2-4.
>
> v4->v5:
>   - Fix the UP panic problem reported by 0day test by unifying the SMP
>     and UP code.
>   - Add patch 5 to add a new kernel config parameter to allow disabling
>     per-cpu list for small systems that won't benefit much from this
>     feature.
>
> v3->v4:
>   - Fix some racing conditions in the code.
>   - Add another patch from Jan to replace list_for_each_entry_safe()
>     by list_for_each_entry().
>   - Add lockdep annotation.
>
> v2->v3:
>   - Directly replace list_for_each_entry() and
>     list_for_each_entry_safe() by pcpu_list_iterate() and
>     pcpu_list_iterate_safe() respectively instead. Those 2 functions
>     provide a stateful per-cpu list iteration interface.
>   - Include Jan Kara's patch to clean up the fsnotify_unmount_inodes()
>     function.
>
> v1->v2:
>   - Use separate structures for list head and nodes&  provide a
>     cleaner interface.
>   - Use existing list_for_each_entry() or list_for_each_entry_safe()
>     macros for each of the sb's s_inodes iteration functions instead
>     of using list_for_each_entry_safe() for all of them which may not
>     be safe in some cases.
>   - Use an iterator interface to access all the nodes of a group of
>     per-cpu lists. This approach is cleaner than the previous double-for
>     macro which is kind of hacky. However, it does require more lines
>     of code changes.
>   - Add a preparatory patch 2 to extract out the per-inode codes from
>     the superblock s_inodes list iteration functions to minimize code
>     changes needed in the patch 3.
>
> This patch is a replacement of my previous list batching patch -
> https://lwn.net/Articles/674105/. Compared with the previous patch,
> this one provides better performance and fairness. However, it also
> requires a bit more changes in the VFS layer.
>
> This patchset is a derivative of Andi Kleen's patch on "Initial per
> cpu list for the per sb inode list"
>
> https://git.kernel.org/cgit/linux/kernel/git/ak/linux-misc.git/commit/?h=hle315/
> combined&id=f1cf9e715a40f44086662ae3b29f123cf059cbf4
>
> Patch 1 introduces the per-cpu list.
>
> Patch 2 cleans up the fsnotify_unmount_inodes() function by making
> the code simpler and more standard.
>
> Patch 3 replaces the use of list_for_each_entry_safe() in
> evict_inodes() and invalidate_inodes() by list_for_each_entry().
>
> Patch 4 modifies the superblock and inode structures to use the per-cpu
> list. The corresponding functions that reference those structures
> are modified.
>
> Jan Kara (2):
>    fsnotify: Simplify inode iteration on umount
>    vfs: Remove unnecessary list_for_each_entry_safe() variants
>
> Waiman Long (2):
>    lib/percpu-list: Per-cpu list with associated per-cpu locks
>    vfs: Use per-cpu list for superblock's inode list
>
>

Hi, I am resending this patch series as I haven't received any feedback 
to see if further change is needed or is good enough to get merged.

Cheers,
Longman