[ Cover-letter is identical to v2, including benchmark results, excluding the change log. ] Currently, local and remote TLB flushes are not performed concurrently, which introduces unnecessary overhead - each INVLPG can take 100s of cycles. This patch-set allows TLB flushes to be run concurrently: first request the remote CPUs to initiate the flush, then run it locally, and finally wait for the remote CPUs to finish their work. In addition, there are various small optimizations to avoid unwarranted false-sharing and atomic operations. The proposed changes should also improve the performance of other invocations of on_each_cpu(). Hopefully, no one has relied on this behavior of on_each_cpu() that invoked functions first remotely and only then locally [Peter says he remembers someone might do so, but without further information it is hard to know how to address it]. Running sysbench on dax/ext4 w/emulated-pmem, write-cache disabled on 2-socket, 48-logical-cores (24+SMT) Haswell-X, 5 repetitions: sysbench fileio --file-total-size=3G --file-test-mode=rndwr \ --file-io-mode=mmap --threads=X --file-fsync-mode=fdatasync run Th. tip-jun28 avg (stdev) +patch-set avg (stdev) change --- --------------------- ---------------------- ------ 1 1267765 (14146) 1299253 (5715) +2.4% 2 1734644 (11936) 1799225 (19577) +3.7% 4 2821268 (41184) 2919132 (40149) +3.4% 8 4171652 (31243) 4376925 (65416) +4.9% 16 5590729 (24160) 5829866 (8127) +4.2% 24 6250212 (24481) 6522303 (28044) +4.3% 32 3994314 (26606) 4077543 (10685) +2.0% 48 4345177 (28091) 4417821 (41337) +1.6% (Note that on configurations with up to 24 threads numactl was used to set all threads on socket 1, which explains the drop in performance when going to 32 threads). Running the same benchmark with security mitigations disabled (PTI, Spectre, MDS): Th. tip-jun28 avg (stdev) +patch-set avg (stdev) change --- --------------------- ---------------------- ------ 1 1598896 (5174) 1607903 (4091) +0.5% 2 2109472 (17827) 2224726 (4372) +5.4% 4 3448587 (11952) 3668551 (30219) +6.3% 8 5425778 (29641) 5606266 (33519) +3.3% 16 6931232 (34677) 7054052 (27873) +1.7% 24 7612473 (23482) 7783138 (13871) +2.2% 32 4296274 (18029) 4283279 (32323) -0.3% 48 4770029 (35541) 4764760 (13575) -0.1% Presumably, PTI requires two invalidations of each mapping, which allows to get higher benefits from concurrency when PTI is on. At the same time, when mitigations are on, other overheads reduce the potential speedup. I tried to reduce the size of the code of the main patch, which required restructuring of the series. v2 -> v3: * Open-code the remote/local-flush decision code [Andy] * Fix hyper-v, Xen implementations [Andrew] * Fix redundant TLB flushes. v1 -> v2: * Removing the patches that Thomas took [tglx] * Adding hyper-v, Xen compile-tested implementations [Dave] * Removing UV [Andy] * Adding lazy optimization, removing inline keyword [Dave] * Restructuring patch-set RFCv2 -> v1: * Fix comment on flush_tlb_multi [Juergen] * Removing async invalidation optimizations [Andy] * Adding KVM support [Paolo] Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Cc: Juergen Gross <jgross@xxxxxxxx> Cc: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxxx> Cc: Sasha Levin <sashal@xxxxxxxxxx> Cc: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: kvm@xxxxxxxxxxxxxxx Cc: linux-hyperv@xxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx Cc: x86@xxxxxxxxxx Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx Nadav Amit (9): smp: Run functions concurrently in smp_call_function_many() x86/mm/tlb: Remove reason as argument for flush_tlb_func_local() x86/mm/tlb: Open-code on_each_cpu_cond_mask() for tlb_is_not_lazy() x86/mm/tlb: Flush remote and local TLBs concurrently x86/mm/tlb: Privatize cpu_tlbstate x86/mm/tlb: Do not make is_lazy dirty for no reason cpumask: Mark functions as pure x86/mm/tlb: Remove UV special case x86/mm/tlb: Remove unnecessary uses of the inline keyword arch/x86/hyperv/mmu.c | 10 +- arch/x86/include/asm/paravirt.h | 6 +- arch/x86/include/asm/paravirt_types.h | 4 +- arch/x86/include/asm/tlbflush.h | 47 ++++----- arch/x86/include/asm/trace/hyperv.h | 2 +- arch/x86/kernel/kvm.c | 11 ++- arch/x86/kernel/paravirt.c | 2 +- arch/x86/mm/init.c | 2 +- arch/x86/mm/tlb.c | 133 ++++++++++++++++---------- arch/x86/xen/mmu_pv.c | 11 +-- include/linux/cpumask.h | 6 +- include/linux/smp.h | 27 ++++-- include/trace/events/xen.h | 2 +- kernel/smp.c | 133 ++++++++++++-------------- 14 files changed, 218 insertions(+), 178 deletions(-) -- 2.20.1 _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
