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Date: Thu, 11 Apr 2019 11:34:26 +1000
From: "Tobin C. Harding" <tobin@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: "Tobin C. Harding" <tobin@...nel.org>,
Roman Gushchin <guro@...com>,
Alexander Viro <viro@....linux.org.uk>,
Christoph Hellwig <hch@...radead.org>,
Pekka Enberg <penberg@...helsinki.fi>,
David Rientjes <rientjes@...gle.com>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
Christopher Lameter <cl@...ux.com>,
Matthew Wilcox <willy@...radead.org>,
Miklos Szeredi <mszeredi@...hat.com>,
Andreas Dilger <adilger@...ger.ca>,
Waiman Long <longman@...hat.com>,
Tycho Andersen <tycho@...ho.ws>,
"Theodore Ts'o" <tytso@....edu>, Andi Kleen <ak@...ux.intel.com>,
David Chinner <david@...morbit.com>,
Nick Piggin <npiggin@...il.com>,
Rik van Riel <riel@...hat.com>,
Hugh Dickins <hughd@...gle.com>,
Jonathan Corbet <corbet@....net>, linux-mm@...ck.org,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [RFC PATCH v3 00/15] Slab Movable Objects (SMO)
Hi,
Another iteration of the SMO patch set implementing suggestions from Al
and Willy on the last version as well as some feedback from comments on
the recent LWN article.
Applies on top of Linus' tree (tag: v5.1-rc4).
This is a patch set implementing movable objects within the SLUB
allocator. This is work based on Christopher Lameter's patch set:
https://lore.kernel.org/patchwork/project/lkml/list/?series=377335
The original code logic is from that set and implemented by Christopher.
Clean up, refactoring, documentation, and additional features by myself.
Responsibility for any bugs remaining falls solely with myself.
Patch #9 has changes to the XArray migration function as suggested by
Matthew, thank you.
The only other changes to this version are to the dcache code.
dcache
------
It was noted on LWN that calling the dcache migration function
'd_migrate' is a misnomer because we are _not_ trying to migrate the
dentry objects but rather only free them. As noted by Al dentry (and
inode) objects are inherently not relocatable. What we are trying to
achieve here is, rather, to attempt to free a select group of dentry
objects. The dcache patches are not intended to be a silver bullet
fixing all fragmentation within the dentry slab cache. Instead we are
trying to make a non-invasive attempt at freeing up pages sparsely used
by the dentry slab cache. This may be useful for a number of reasons
e.g. we _may_ be able to free a page that is stopping high order page
allocations. This would be a useful capability.
Since this is only something that _may_ help the aim is to be
non-intrusive. This version of the set adds a config option to
selectively build in the SMO stuff for the dcache. Without this option
the only change this set makes to the dcache is adding a constructor.
With the constructor doing a spinlock_init() it is hoped this will at
best be a performance gain and at worst NOT be a performance reduction.
Benchmarking has found this to be the case, results are included below.
Patch #14 and #15 can be rolled into a single patch if #15 is found
favourable.
Changes since v2:
- Improve the XArray migration function (thanks Matthew)
- Fix the dcache constructor (thanks Alexander)
- Rename the d_migrate function to d_partial_shrink (open to
suggested improvement)
- Totally re-write the dcache migration function based on schooling by Al
Thanks for looking at this,
Tobin.
=============================
dcache SMO patch benchmarking
=============================
Process
=======
We use 5.1-rc4 as the baseline. We benchmark the SMO patchset with
and without CONFIG_DCACHE_SMO. SMO patch set without CONFIG_DCACHE_SMO
just adds a constructor to the dcache, no other code added to the build.
Building with CONFIG_DCACHE_SMO adds code to enable object migration for
the dcache.
cmd = `time find / -name fname-no-exist`
drop_caches = `cat 2 > /proc/sys/vm/drop_caches`
1. Boot system
2. Run $cmd
3. Run $drop_caches
4. Run $cmd
Bare metal results
------------------
Machine: x86_64
Kernel configured with::
make defconfig
- rc4 kernel (baseline)::
time find / -name fname-no-exist dentry
real 0m29.799s
user 0m1.519s
sys 0m10.825s
echo 2 > /proc/sys/vm/drop_caches
time find / -name fname-no-exist dentry
real 0m6.828s
user 0m0.952s
sys 0m5.824s
- rc4 kernel with SMO patch set and !CONFIG_DCACHE_SMO::
time find / -name fname-no-exist
real 0m30.075s
user 0m1.480s
sys 0m10.754s
echo 2 > /proc/sys/vm/drop_caches
time find / -name fname-no-existproc/sys/vm/drop_caches
real 0m6.626s
user 0m0.917s
sys 0m5.661s
- rc4 kernel with SMO patch set and CONFIG_DCACHE_SMO::
time find / -name fname-no-exist dentry
real 0m30.637s
user 0m1.516s
sys 0m11.603s
echo 2 > /proc/sys/vm/drop_caches
time find / -name fname-no-exist dentry
real 0m6.886s
user 0m0.932s
sys 0m5.907s
Qemu results
------------
Host machine: x86_64
Qemu kernel configured with::
make defconfig
make kvmconfig
Qemu invoked with::
qemu-system-x86_64 \
-enable-kvm \
-m 4G \
-hda arch.qcow \
-kernel $kernel \
-serial stdio \
-display none" \
-append 'root=/dev/sda1 console=ttyS0 rw'
- rc4 kernel (baseline)::
time find / -name fname-no-exist
real 0m0.929s
user 0m0.096s
sys 0m0.168s
echo 2 > /proc/sys/vm/drop_caches
time find / -name fname-no-exist
real 0m0.249s
user 0m0.112s
sys 0m0.133s
- rc4 kernel with SMO patch set and !CONFIG_DCACHE_SMO::
time find / -name fname-no-exist
real 0m1.018s
user 0m0.095s
sys 0m0.151s
echo 2 > /proc/sys/vm/drop_caches
time find / -name fname-no-exist
real 0m0.191s
user 0m0.083s
sys 0m0.105s
- rc4 kernel with SMO patch set and CONFIG_DCACHE_SMO::
time find / -name fname-no-exist
real 0m0.763s
user 0m0.091s
sys 0m0.165s
echo 2 > /proc/sys/vm/drop_caches
time find / -name fname-no-exist
real 0m0.192s
user 0m0.062s
sys 0m0.126s
I am not very experienced with benchmarking, if this is grossly
incorrect please do not hesitate to yell at me. Any suggestions on
more/better benchmarking most appreciated.
Thanks,
Tobin.
Tobin C. Harding (15):
slub: Add isolate() and migrate() methods
tools/vm/slabinfo: Add support for -C and -M options
slub: Sort slab cache list
slub: Slab defrag core
tools/vm/slabinfo: Add remote node defrag ratio output
tools/vm/slabinfo: Add defrag_used_ratio output
tools/testing/slab: Add object migration test module
tools/testing/slab: Add object migration test suite
xarray: Implement migration function for objects
tools/testing/slab: Add XArray movable objects tests
slub: Enable moving objects to/from specific nodes
slub: Enable balancing slabs across nodes
dcache: Provide a dentry constructor
dcache: Implement partial shrink via Slab Movable Objects
dcache: Add CONFIG_DCACHE_SMO
Documentation/ABI/testing/sysfs-kernel-slab | 14 +
fs/dcache.c | 106 ++-
include/linux/slab.h | 71 ++
include/linux/slub_def.h | 10 +
lib/radix-tree.c | 13 +
lib/xarray.c | 49 ++
mm/Kconfig | 14 +
mm/slab_common.c | 2 +-
mm/slub.c | 819 ++++++++++++++++++--
tools/testing/slab/Makefile | 10 +
tools/testing/slab/slub_defrag.c | 567 ++++++++++++++
tools/testing/slab/slub_defrag.py | 451 +++++++++++
tools/testing/slab/slub_defrag_xarray.c | 211 +++++
tools/vm/slabinfo.c | 51 +-
14 files changed, 2295 insertions(+), 93 deletions(-)
create mode 100644 tools/testing/slab/Makefile
create mode 100644 tools/testing/slab/slub_defrag.c
create mode 100755 tools/testing/slab/slub_defrag.py
create mode 100644 tools/testing/slab/slub_defrag_xarray.c
--
2.21.0
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