Hello. On čtvrtek 6. února 2025 5:43:19, středoevropský standardní čas Rik van Riel wrote: > Add support for broadcast TLB invalidation using AMD's INVLPGB instruction. > > This allows the kernel to invalidate TLB entries on remote CPUs without > needing to send IPIs, without having to wait for remote CPUs to handle > those interrupts, and with less interruption to what was running on > those CPUs. > > Because x86 PCID space is limited, and there are some very large > systems out there, broadcast TLB invalidation is only used for > processes that are active on 3 or more CPUs, with the threshold > being gradually increased the more the PCID space gets exhausted. > > Combined with the removal of unnecessary lru_add_drain calls > (see https://lkml.org/lkml/2024/12/19/1388) this results in a > nice performance boost for the will-it-scale tlb_flush2_threads > test on an AMD Milan system with 36 cores: > > - vanilla kernel: 527k loops/second > - lru_add_drain removal: 731k loops/second > - only INVLPGB: 527k loops/second > - lru_add_drain + INVLPGB: 1157k loops/second > > Profiling with only the INVLPGB changes showed while > TLB invalidation went down from 40% of the total CPU > time to only around 4% of CPU time, the contention > simply moved to the LRU lock. > > Fixing both at the same time about doubles the > number of iterations per second from this case. > > Some numbers closer to real world performance > can be found at Phoronix, thanks to Michael: > > https://www.phoronix.com/news/AMD-INVLPGB-Linux-Benefits > > My current plan is to implement support for Intel's RAR > (Remote Action Request) TLB flushing in a follow-up series, > after this thing has been merged into -tip. Making things > any larger would just be unwieldy for reviewers. > > v9: > - print warning when start or end address was rounded (Peter) OK, I've just hit one: TLB flush not stride 200000 aligned. Start 7fffc0000000, end 7fffffe01000 WARNING: CPU: 31 PID: 411 at arch/x86/mm/tlb.c:1342 flush_tlb_mm_range+0x57b/0x600 Modules linked in: CPU: 31 UID: 0 PID: 411 Comm: modprobe Not tainted 6.13.0-pf3 #1 1366679ca06f46d05d1e9d9c537b0c6b4c922b82 Hardware name: ASUS System Product Name/Pro WS X570-ACE, BIOS 4902 08/29/2024 RIP: 0010:flush_tlb_mm_range+0x57b/0x600 Code: 5f e9 39 b3 3f 00 e8 24 57 f5 ff e9 e9 fc ff ff 48 8b 0c 24 4c 89 e2 48 c7 c7 78 59 27 b0 c6 05 3d 1a 31 02 01 e8 85 e4 01 00 <0f> 0b e9 35 fb ff ff fa 0f 1f 44 00 00 48 89 df e8 a0 f4 ff ff fb RSP: 0018:ffffc137c11e7a38 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffff9e6eaf1b5d80 RCX: 00000000ffffdfff RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001 RBP: ffff9e500244d800 R08: 00000000ffffdfff R09: ffff9e6eae1fffa8 R10: 00000000ffffdfff R11: 0000000000000003 R12: 00007fffc0000000 R13: 000000000000001f R14: 0000000000000015 R15: ffff9e6eaf180000 FS: 0000000000000000(0000) GS:ffff9e6eaf180000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000109966000 CR4: 0000000000f50ef0 PKRU: 55555554 Call Trace: <TASK> tlb_flush_mmu+0x125/0x1a0 tlb_finish_mmu+0x41/0x80 relocate_vma_down+0x183/0x200 setup_arg_pages+0x201/0x390 load_elf_binary+0x3a7/0x17d0 bprm_execve+0x244/0x630 kernel_execve+0x180/0x1f0 call_usermodehelper_exec_async+0xd0/0x190 ret_from_fork+0x34/0x50 ret_from_fork_asm+0x1a/0x30 </TASK> What do I do with it? Thank you. > - in the reclaim code, tlbsync at context switch time (Peter) > - fix !CONFIG_CPU_SUP_AMD compile error in arch_tlbbatch_add_pending (Jan) > v8: > - round start & end to handle non-page-aligned callers (Steven & Jan) > - fix up changelog & add tested-by tags (Manali) > v7: > - a few small code cleanups (Nadav) > - fix spurious VM_WARN_ON_ONCE in mm_global_asid > - code simplifications & better barriers (Peter & Dave) > v6: > - fix info->end check in flush_tlb_kernel_range (Michael) > - disable broadcast TLB flushing on 32 bit x86 > v5: > - use byte assembly for compatibility with older toolchains (Borislav, Michael) > - ensure a panic on an invalid number of extra pages (Dave, Tom) > - add cant_migrate() assertion to tlbsync (Jann) > - a bunch more cleanups (Nadav) > - key TCE enabling off X86_FEATURE_TCE (Andrew) > - fix a race between reclaim and ASID transition (Jann) > v4: > - Use only bitmaps to track free global ASIDs (Nadav) > - Improved AMD initialization (Borislav & Tom) > - Various naming and documentation improvements (Peter, Nadav, Tom, Dave) > - Fixes for subtle race conditions (Jann) > v3: > - Remove paravirt tlb_remove_table call (thank you Qi Zheng) > - More suggested cleanups and changelog fixes by Peter and Nadav > v2: > - Apply suggestions by Peter and Borislav (thank you!) > - Fix bug in arch_tlbbatch_flush, where we need to do both > the TLBSYNC, and flush the CPUs that are in the cpumask. > - Some updates to comments and changelogs based on questions. -- Oleksandr Natalenko, MSE
Attachment:
signature.asc
Description: This is a digitally signed message part.
