3 commits

Author	SHA1	Message	Date
Srikar Dronamraju	ca3f969dcb	powerpc/paravirt: Use is_kvm_guest() in vcpu_is_preempted() ... If its a shared LPAR but not a KVM guest, then see if the vCPU is related to the calling vCPU. On PowerVM, only cores can be preempted. So if one vCPU is a non-preempted state, we can decipher that all other vCPUs sharing the same core are in non-preempted state. Performance results: $ perf stat -r 5 -a perf bench sched pipe -l 10000000 (lesser time is better) powerpc/next 35,107,951.20 msec cpu-clock # 255.898 CPUs utilized ( +- 0.31% ) 23,655,348 context-switches # 0.674 K/sec ( +- 3.72% ) 14,465 cpu-migrations # 0.000 K/sec ( +- 5.37% ) 82,463 page-faults # 0.002 K/sec ( +- 8.40% ) 1,127,182,328,206 cycles # 0.032 GHz ( +- 1.60% ) (66.67%) 78,587,300,622 stalled-cycles-frontend # 6.97% frontend cycles idle ( +- 0.08% ) (50.01%) 654,124,218,432 stalled-cycles-backend # 58.03% backend cycles idle ( +- 1.74% ) (50.01%) 834,013,059,242 instructions # 0.74 insn per cycle # 0.78 stalled cycles per insn ( +- 0.73% ) (66.67%) 132,911,454,387 branches # 3.786 M/sec ( +- 0.59% ) (50.00%) 2,890,882,143 branch-misses # 2.18% of all branches ( +- 0.46% ) (50.00%) 137.195 +- 0.419 seconds time elapsed ( +- 0.31% ) powerpc/next + patchset 29,981,702.64 msec cpu-clock # 255.881 CPUs utilized ( +- 1.30% ) 40,162,456 context-switches # 0.001 M/sec ( +- 0.01% ) 1,110 cpu-migrations # 0.000 K/sec ( +- 5.20% ) 62,616 page-faults # 0.002 K/sec ( +- 3.93% ) 1,430,030,626,037 cycles # 0.048 GHz ( +- 1.41% ) (66.67%) 83,202,707,288 stalled-cycles-frontend # 5.82% frontend cycles idle ( +- 0.75% ) (50.01%) 744,556,088,520 stalled-cycles-backend # 52.07% backend cycles idle ( +- 1.39% ) (50.01%) 940,138,418,674 instructions # 0.66 insn per cycle # 0.79 stalled cycles per insn ( +- 0.51% ) (66.67%) 146,452,852,283 branches # 4.885 M/sec ( +- 0.80% ) (50.00%) 3,237,743,996 branch-misses # 2.21% of all branches ( +- 1.18% ) (50.01%) 117.17 +- 1.52 seconds time elapsed ( +- 1.30% ) This is around 14.6% improvement in performance. Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: Waiman Long <longman@redhat.com> [mpe: Fold in performance results from cover letter] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20201202050456.164005-5-srikar@linux.vnet.ibm.com	2020-12-04 01:01:22 +11:00
Nicholas Piggin	20c0e8269e	powerpc/pseries: Implement paravirt qspinlocks for SPLPAR ... This implements the generic paravirt qspinlocks using H_PROD and H_CONFER to kick and wait. This uses an un-directed yield to any CPU rather than the directed yield to a pre-empted lock holder that paravirtualised simple spinlocks use, that requires no kick hcall. This is something that could be investigated and improved in future. Performance results can be found in the commit which added queued spinlocks. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200724131423.1362108-5-npiggin@gmail.com	2020-07-27 00:01:29 +10:00
Nicholas Piggin	20d444d06f	powerpc/pseries: Move some PAPR paravirt functions to their own file ... These functions will be used by the queued spinlock implementation, and may be useful elsewhere too, so move them out of spinlock.h. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Acked-by: Waiman Long <longman@redhat.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200724131423.1362108-2-npiggin@gmail.com	2020-07-26 23:34:26 +10:00