powerpc/64s/slb: Add no_slb_preload early cmdline param

no_slb_preload cmdline can come useful in quickly disabling and/or
testing the performance impact of userspace slb preloads. Recently there
was a slb multi-hit issue due to slb preload cache which was very
difficult to triage. This cmdline option allows to quickly disable
preloads and verify if the issue exists in preload cache or somewhere
else. This can also be a useful option to see the effect of slb preloads
for any application workload e.g. number of slb faults with or w/o slb
preloads.

with slb_preload:
slb_faults (minimal initrd boot): 15
slb_faults (full systemd boot): 300

with no_slb_preload:
slb_faults (minimal initrd boot): 33
slb_faults (full systemd boot): 138180

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/de484b55c45d831bc2db63945f455153c89a9a65.1761834163.git.ritesh.list@gmail.com
This commit is contained in:
Ritesh Harjani (IBM)
2025-10-30 20:27:36 +05:30
committed by Madhavan Srinivasan
parent 2a492d6b38
commit 5b3a426aff
4 changed files with 28 additions and 0 deletions

View File

@@ -7192,6 +7192,9 @@
them frequently to increase the rate of SLB faults
on kernel addresses.
no_slb_preload [PPC,EARLY]
Disables slb preloading for userspace.
sunrpc.min_resvport=
sunrpc.max_resvport=
[NFS,SUNRPC]