From: Mikael Pettersson This 3-part patch set widens the counter 'start' fields in the mmap()-visible state from 32 to 64 bits, to prepare for future processors that may need that extra precision. This would bump the size of the pmc[] array elements to 24 bytes, of which only 20 would be used, so the 'map' fields in that array are removed -- the kernel can retrive that data from the control structure instead, and user-space can also maintain it itself. This brings the pmc[] array elements down to 16 bytes again, with 100% utilisation. The removal of the 'cstatus' field from the user-visible state that David Gibson proposed has not been done. The problem is that cstatus also exposes asynchronous state changes (in particular at overflow interrupts), and I'm not yet convinced that user-space can handle its removal without undue burden. perfctr x86 ABI update: - : In user-visible state, make start fields 64 bits (for future-proofing the ABI). Remove map field from pmc[] array to avoid underutilised cache lines. - x86.c: retrieve mapping from ->control.pmc_map[]. Signed-off-by: Mikael Pettersson Signed-off-by: Andrew Morton --- 25-akpm/drivers/perfctr/x86.c | 24 ++++++++++-------------- 25-akpm/include/asm-i386/perfctr.h | 10 ++++------ 2 files changed, 14 insertions(+), 20 deletions(-) diff -puN drivers/perfctr/x86.c~perfctr-x86-abi-update drivers/perfctr/x86.c --- 25/drivers/perfctr/x86.c~perfctr-x86-abi-update 2005-04-10 15:11:01.000000000 -0700 +++ 25-akpm/drivers/perfctr/x86.c 2005-04-10 15:11:01.000000000 -0700 @@ -1,4 +1,4 @@ -/* $Id: x86.c,v 1.155 2005/03/13 13:55:58 mikpe Exp $ +/* $Id: x86.c,v 1.158 2005/04/08 14:36:49 mikpe Exp $ * x86/x86_64 performance-monitoring counters driver. * * Copyright (C) 1999-2005 Mikael Pettersson @@ -242,7 +242,6 @@ static int p5_like_check_control(struct cesr_half[1] = 0; for(i = 0; i < state->control.header.nractrs; ++i) { pmc = state->control.pmc_map[i]; - state->user.pmc[i].map = pmc; if (pmc > 1 || cesr_half[pmc] != 0) return -EINVAL; evntsel = state->control.evntsel[0]; @@ -298,7 +297,7 @@ static void p5_read_counters(const struc rdtscl(ctrs->tsc); nrctrs = perfctr_cstatus_nractrs(cstatus); for(i = 0; i < nrctrs; ++i) { - unsigned int pmc = state->user.pmc[i].map; + unsigned int pmc = state->control.pmc_map[i]; rdmsr_low(MSR_P5_CTR0+pmc, ctrs->pmc[i]); } } @@ -314,7 +313,7 @@ static void rdpmc_read_counters(const st rdtscl(ctrs->tsc); nrctrs = perfctr_cstatus_nractrs(cstatus); for(i = 0; i < nrctrs; ++i) { - unsigned int pmc = state->user.pmc[i].map; + unsigned int pmc = state->control.pmc_map[i]; rdpmc_low(pmc, ctrs->pmc[i]); } } @@ -412,7 +411,6 @@ static int p6_like_check_control(struct pmc_mask = 0; for(i = 0; i < nrctrs; ++i) { pmc = state->control.pmc_map[i]; - state->user.pmc[i].map = pmc; if (pmc >= (is_k7 ? 4 : 2) || (pmc_mask & (1<user.pmc[i].map; + pmc_raw = state->control.pmc_map[i]; /* Note: P4_MASK_FAST_RDPMC is a no-op for P6 and K7. We don't need to make it into a parameter. */ pmc_idx = pmc_raw & P4_MASK_FAST_RDPMC; @@ -516,7 +514,7 @@ static void p6_like_iresume(const struct for(i = perfctr_cstatus_nractrs(cstatus); i < nrctrs; ++i) { /* Note: P4_MASK_FAST_RDPMC is a no-op for P6 and K7. We don't need to make it into a parameter. */ - unsigned int pmc = state->user.pmc[i].map & P4_MASK_FAST_RDPMC; + unsigned int pmc = state->control.pmc_map[i] & P4_MASK_FAST_RDPMC; /* If the control wasn't ours we must disable the evntsels before reinitialising the counters, to prevent unexpected counter increments and missed overflow interrupts. */ @@ -525,7 +523,7 @@ static void p6_like_iresume(const struct wrmsr(msr_evntsel0+pmc, 0, 0); } /* P4 erratum N15 does not apply since the CCCR is disabled. */ - wrmsr(msr_perfctr0+pmc, state->user.pmc[i].start, -1); + wrmsr(msr_perfctr0+pmc, (unsigned int)state->user.pmc[i].start, -1); } /* cache->id remains != state->id */ } @@ -553,7 +551,7 @@ static void p6_like_write_control(const return; nrctrs = perfctr_cstatus_nrctrs(state->user.cstatus); for(i = 0; i < nrctrs; ++i) { - unsigned int pmc = state->user.pmc[i].map; + unsigned int pmc = state->control.pmc_map[i]; unsigned int evntsel = state->control.evntsel[pmc]; if (evntsel != cache->control.evntsel[pmc]) { cache->control.evntsel[pmc] = evntsel; @@ -639,7 +637,6 @@ static int vc3_check_control(struct perf if (state->control.header.nractrs == 1) { if (state->control.pmc_map[0] != 1) return -EINVAL; - state->user.pmc[0].map = 1; if (state->control.evntsel[1] & VC3_EVNTSEL1_RESERVED) return -EPERM; state->id = state->control.evntsel[1]; @@ -765,7 +762,6 @@ static int p4_check_control(struct perfc pmc_map[i] is what we pass to RDPMC, the PMC itself is extracted by masking off the FAST_RDPMC flag */ pmc = state->control.pmc_map[i] & ~P4_FAST_RDPMC; - state->user.pmc[i].map = state->control.pmc_map[i]; if (pmc >= 18 || (pmc_mask & (1<control.escr[escr_off] = escr_val; wrmsr(MSR_P4_ESCR0+escr_off, escr_val, 0); } - pmc = state->user.pmc[i].map & P4_MASK_FAST_RDPMC; + pmc = state->control.pmc_map[i] & P4_MASK_FAST_RDPMC; cccr_val = state->control.evntsel[pmc]; if (cccr_val != cache->control.evntsel[pmc]) { cache->control.evntsel[pmc] = cccr_val; @@ -1000,7 +996,7 @@ unsigned int perfctr_cpu_identify_overfl pmc_mask = 0; for(i = perfctr_cstatus_nractrs(cstatus); i < nrctrs; ++i) { if ((int)state->user.pmc[i].start >= 0) { /* XXX: ">" ? */ - unsigned int pmc = state->user.pmc[i].map & P4_MASK_FAST_RDPMC; + unsigned int pmc = state->control.pmc_map[i] & P4_MASK_FAST_RDPMC; /* XXX: "+=" to correct for overshots */ state->user.pmc[i].start = state->control.ireset[pmc]; pmc_mask |= (1 << i); @@ -1022,7 +1018,7 @@ static inline int check_ireset(struct pe i = state->control.header.nractrs; nrctrs = i + state->control.header.nrictrs; for(; i < nrctrs; ++i) { - unsigned int pmc = state->user.pmc[i].map & P4_MASK_FAST_RDPMC; + unsigned int pmc = state->control.pmc_map[i] & P4_MASK_FAST_RDPMC; if ((int)state->control.ireset[pmc] >= 0) return -EINVAL; state->user.pmc[i].start = state->control.ireset[pmc]; diff -puN include/asm-i386/perfctr.h~perfctr-x86-abi-update include/asm-i386/perfctr.h --- 25/include/asm-i386/perfctr.h~perfctr-x86-abi-update 2005-04-10 15:11:01.000000000 -0700 +++ 25-akpm/include/asm-i386/perfctr.h 2005-04-10 15:11:01.000000000 -0700 @@ -1,4 +1,4 @@ -/* $Id: perfctr.h,v 1.61 2005/03/17 23:57:10 mikpe Exp $ +/* $Id: perfctr.h,v 1.63 2005/04/08 14:36:49 mikpe Exp $ * x86/x86_64 Performance-Monitoring Counters driver * * Copyright (C) 1999-2005 Mikael Pettersson @@ -21,13 +21,11 @@ struct perfctr_cpu_control_header { struct perfctr_cpu_state_user { __u32 cstatus; - /* The two tsc fields must be inlined. Placing them in a - sub-struct causes unwanted internal padding on x86-64. */ - __u32 tsc_start; + __u32 _filler; + __u64 tsc_start; __u64 tsc_sum; struct { - __u32 map; - __u32 start; + __u64 start; __u64 sum; } pmc[18]; /* the size is not part of the user ABI */ }; _