lib/group_cpus: make group CPU cluster aware #479
+206
−65
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Author
|
Upstream branch: 623fb99 |
blktests-ci
bot
force-pushed
the
linus-master_base
branch
from
f962a4d to
06634b5
Compare
Author
|
Upstream branch: b543459 |
blktests-ci
bot
force-pushed
the
series/1041509=>linus-master
branch
from
39d284f to
2b8956e
Compare
blktests-ci
bot
force-pushed
the
linus-master_base
branch
from
06634b5 to
8a473ad
Compare
As CPU core counts increase, the number of NVMe IRQs may be smaller than
the total number of CPUs. This forces multiple CPUs to share the same
IRQ. If the IRQ affinity and the CPU’s cluster do not align, a
performance penalty can be observed on some platforms.
This patch improves IRQ affinity by grouping CPUs by cluster within each
NUMA domain, ensuring better locality between CPUs and their assigned
NVMe IRQs.
Details:
Intel Xeon E platform packs 4 CPU cores as 1 module (cluster) and share
the L2 cache. Let's say, if there are 40 CPUs in 1 NUMA domain and 11
IRQs to dispatch. The existing algorithm will map first 7 IRQs each with
4 CPUs and remained 4 IRQs each with 3 CPUs. The last 4 IRQs may
have cross cluster issue. For example, the 9th IRQ which pinned to
CPU32, then for CPU31, it will have cross L2 memory access.
CPU |28 29 30 31|32 33 34 35|36 ...
-------- -------- --------
IRQ 8 9 10
If this patch applied, then first 2 IRQs each mapped with 2 CPUs and
rest 9 IRQs each mapped with 4 CPUs, which avoids the cross cluster
memory access.
CPU |00 01 02 03|04 05 06 07|08 09 10 11| ...
----- ----- ----------- -----------
IRQ 1 2 3 4
As a result, 15%+ performance difference is observed in FIO
libaio/randread/bs=8k.
Changes since V1:
- Add more performance details in commit messages.
- Fix endless loop when topology_cluster_cpumask return invalid mask.
History:
v1: https://lore.kernel.org/all/20251024023038.872616-1-wangyang.guo@intel.com/
v1 [RESEND]: https://lore.kernel.org/all/20251111020608.1501543-1-wangyang.guo@intel.com/
Reviewed-by: Tianyou Li <tianyou.li@intel.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Tested-by: Dan Liang <dan.liang@intel.com>
Signed-off-by: Wangyang Guo <wangyang.guo@intel.com>
Author
|
Upstream branch: 944aacb |
blktests-ci
bot
force-pushed
the
series/1041509=>linus-master
branch
from
2b8956e to
537b8ee
Compare
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Pull request for series with
subject: lib/group_cpus: make group CPU cluster aware
version: 2
url: https://patchwork.kernel.org/project/linux-block/list/?series=1041509