Message ID | 1532699493-10883-1-git-send-email-ldufour@linux.vnet.ibm.com (mailing list archive) |
---|---|
Headers | show |
Series | powerpc/pseries: use H_BLOCK_REMOVE | expand |
On Fri, 27 Jul 2018 15:51:30 +0200 Laurent Dufour <ldufour@linux.vnet.ibm.com> wrote: > [Resending so everyone is getting the cover letter] > > On very large system we could see soft lockup fired when a process is exiting > > watchdog: BUG: soft lockup - CPU#851 stuck for 21s! [forkoff:215523] > Modules linked in: pseries_rng rng_core xfs raid10 vmx_crypto btrfs libcrc32c xor zstd_decompress zstd_compress xxhash lzo_compress raid6_pq crc32c_vpmsum lpfc crc_t10dif crct10dif_generic crct10dif_common dm_multipath scsi_dh_rdac scsi_dh_alua autofs4 > CPU: 851 PID: 215523 Comm: forkoff Not tainted 4.17.0 #1 > NIP: c0000000000b995c LR: c0000000000b8f64 CTR: 000000000000aa18 > REGS: c00006b0645b7610 TRAP: 0901 Not tainted (4.17.0) > MSR: 800000010280b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE,TM[E]> CR: 22042082 XER: 00000000 > CFAR: 00000000006cf8f0 SOFTE: 0 > GPR00: 0010000000000000 c00006b0645b7890 c000000000f99200 0000000000000000 > GPR04: 8e000001a5a4de58 400249cf1bfd5480 8e000001a5a4de50 400249cf1bfd5480 > GPR08: 8e000001a5a4de48 400249cf1bfd5480 8e000001a5a4de40 400249cf1bfd5480 > GPR12: ffffffffffffffff c00000001e690800 > NIP [c0000000000b995c] plpar_hcall9+0x44/0x7c > LR [c0000000000b8f64] pSeries_lpar_flush_hash_range+0x324/0x3d0 > Call Trace: > [c00006b0645b7890] [8e000001a5a4dd20] 0x8e000001a5a4dd20 (unreliable) > [c00006b0645b7a00] [c00000000006d5b0] flush_hash_range+0x60/0x110 > [c00006b0645b7a50] [c000000000072a2c] __flush_tlb_pending+0x4c/0xd0 > [c00006b0645b7a80] [c0000000002eaf44] unmap_page_range+0x984/0xbd0 > [c00006b0645b7bc0] [c0000000002eb594] unmap_vmas+0x84/0x100 > [c00006b0645b7c10] [c0000000002f8afc] exit_mmap+0xac/0x1f0 > [c00006b0645b7cd0] [c0000000000f2638] mmput+0x98/0x1b0 > [c00006b0645b7d00] [c0000000000fc9d0] do_exit+0x330/0xc00 > [c00006b0645b7dc0] [c0000000000fd384] do_group_exit+0x64/0x100 > [c00006b0645b7e00] [c0000000000fd44c] sys_exit_group+0x2c/0x30 > [c00006b0645b7e30] [c00000000000b960] system_call+0x58/0x6c > Instruction dump: > 60000000 f8810028 7ca42b78 7cc53378 7ce63b78 7d074378 7d284b78 7d495378 > e9410060 e9610068 e9810070 44000022 <7d806378> e9810028 f88c0000 f8ac0008 > > This happens when removing the PTE by calling the hypervisor using the > H_BULK_REMOVE call. This call is processing up to 4 PTEs but is doing a > tlbie for each PTE it is processing. This could lead to long time spent in > the hypervisor (sometimes up to 4s) and soft lockup being raised because > the scheduler is not called in zap_pte_range(). > > Since the Power7's time, the hypervisor is providing a new hcall > H_BLOCK_REMOVE allowing processing up to 8 PTEs with one call to > tlbie. By limiting the amount of tlbie generated, this reduces the time > spent invalidating the PTEs. Oh that's a nice feature. I must have an ancient PAPR because I don't have it. It could be a good project for someone to implement it in KVM too. > > This hcall requires that the pages are "all within the same naturally > aligned 8 page virtual address block". > > With this patch series applied, I couldn't see any soft lockup raised on > the victim LPAR I was running the test one. > > This series is covering both normal pages and huge pages. Really nice, thanks for working on the problem. Thanks, Nick
Nicholas Piggin <npiggin@gmail.com> writes: > On Fri, 27 Jul 2018 15:51:30 +0200 > Laurent Dufour <ldufour@linux.vnet.ibm.com> wrote: >> [Resending so everyone is getting the cover letter] >> On very large system we could see soft lockup fired when a process is exiting >> >> watchdog: BUG: soft lockup - CPU#851 stuck for 21s! [forkoff:215523] >> Modules linked in: pseries_rng rng_core xfs raid10 vmx_crypto btrfs libcrc32c xor zstd_decompress zstd_compress xxhash lzo_compress raid6_pq crc32c_vpmsum lpfc crc_t10dif crct10dif_generic crct10dif_common dm_multipath scsi_dh_rdac scsi_dh_alua autofs4 >> CPU: 851 PID: 215523 Comm: forkoff Not tainted 4.17.0 #1 >> NIP: c0000000000b995c LR: c0000000000b8f64 CTR: 000000000000aa18 >> REGS: c00006b0645b7610 TRAP: 0901 Not tainted (4.17.0) >> MSR: 800000010280b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE,TM[E]> CR: 22042082 XER: 00000000 >> CFAR: 00000000006cf8f0 SOFTE: 0 >> GPR00: 0010000000000000 c00006b0645b7890 c000000000f99200 0000000000000000 >> GPR04: 8e000001a5a4de58 400249cf1bfd5480 8e000001a5a4de50 400249cf1bfd5480 >> GPR08: 8e000001a5a4de48 400249cf1bfd5480 8e000001a5a4de40 400249cf1bfd5480 >> GPR12: ffffffffffffffff c00000001e690800 >> NIP [c0000000000b995c] plpar_hcall9+0x44/0x7c >> LR [c0000000000b8f64] pSeries_lpar_flush_hash_range+0x324/0x3d0 >> Call Trace: >> [c00006b0645b7890] [8e000001a5a4dd20] 0x8e000001a5a4dd20 (unreliable) >> [c00006b0645b7a00] [c00000000006d5b0] flush_hash_range+0x60/0x110 >> [c00006b0645b7a50] [c000000000072a2c] __flush_tlb_pending+0x4c/0xd0 >> [c00006b0645b7a80] [c0000000002eaf44] unmap_page_range+0x984/0xbd0 >> [c00006b0645b7bc0] [c0000000002eb594] unmap_vmas+0x84/0x100 >> [c00006b0645b7c10] [c0000000002f8afc] exit_mmap+0xac/0x1f0 >> [c00006b0645b7cd0] [c0000000000f2638] mmput+0x98/0x1b0 >> [c00006b0645b7d00] [c0000000000fc9d0] do_exit+0x330/0xc00 >> [c00006b0645b7dc0] [c0000000000fd384] do_group_exit+0x64/0x100 >> [c00006b0645b7e00] [c0000000000fd44c] sys_exit_group+0x2c/0x30 >> [c00006b0645b7e30] [c00000000000b960] system_call+0x58/0x6c >> Instruction dump: >> 60000000 f8810028 7ca42b78 7cc53378 7ce63b78 7d074378 7d284b78 7d495378 >> e9410060 e9610068 e9810070 44000022 <7d806378> e9810028 f88c0000 f8ac0008 >> >> This happens when removing the PTE by calling the hypervisor using the >> H_BULK_REMOVE call. This call is processing up to 4 PTEs but is doing a >> tlbie for each PTE it is processing. This could lead to long time spent in >> the hypervisor (sometimes up to 4s) and soft lockup being raised because >> the scheduler is not called in zap_pte_range(). >> >> Since the Power7's time, the hypervisor is providing a new hcall >> H_BLOCK_REMOVE allowing processing up to 8 PTEs with one call to >> tlbie. By limiting the amount of tlbie generated, this reduces the time >> spent invalidating the PTEs. > > Oh that's a nice feature. I must have an ancient PAPR because I don't > have it. The only public document is LoPAPR, which is a stripped down version of the 2012 PAPR. cheers