In message <201910070406.x9746n0u009...@slippy.cwsent.com>, Cy Schubert
writes:
> In message <201910062213.x96mdzv3085...@repo.freebsd.org>, Mateusz Guzik
> writes
> :
> > Author: mjg
> > Date: Sun Oct 6 22:13:35 2019
> > New Revision: 353149
> > URL: https://svnweb.freebsd.org/changeset/base/353149
> >
> > Log:
> > amd64 pmap: implement per-superpage locks
> >
> > The current 256-lock sized array is a problem in the following ways:
> > - it's way too small
> > - there are 2 locks per cacheline
> > - it is not NUMA-aware
> >
> > Solve these issues by introducing per-superpage locks backed by pages
> > allocated from respective domains.
> >
> > This significantly reduces contention e.g. during poudriere -j 104.
> > See the review for results.
> >
> > Reviewed by: kib
> > Discussed with: jeff
> > Sponsored by: The FreeBSD Foundation
> > Differential Revision: https://reviews.freebsd.org/D21833
> >
> > Modified:
> > head/sys/amd64/amd64/pmap.c
> >
> > Modified: head/sys/amd64/amd64/pmap.c
> > ===========================================================================
> ==
> > =
> > --- head/sys/amd64/amd64/pmap.c Sun Oct 6 20:36:25 2019 (r35314
> > 8)
> > +++ head/sys/amd64/amd64/pmap.c Sun Oct 6 22:13:35 2019 (r35314
> > 9)
> > @@ -316,13 +316,25 @@ pmap_pku_mask_bit(pmap_t pmap)
> > #define PV_STAT(x) do { } while (0)
> > #endif
> >
> > -#define pa_index(pa) ((pa) >> PDRSHIFT)
> > +#undef pa_index
> > +#define pa_index(pa) ({ \
> > + KASSERT((pa) <= vm_phys_segs[vm_phys_nsegs - 1].end, \
> > + ("address %lx beyond the last segment", (pa))); \
> > + (pa) >> PDRSHIFT; \
> > +})
> > +#if VM_NRESERVLEVEL > 0
> > +#define pa_to_pmdp(pa) (&pv_table[pa_index(pa)])
> > +#define pa_to_pvh(pa) (&(pa_to_pmdp(pa)->pv_page))
> > +#define PHYS_TO_PV_LIST_LOCK(pa) \
> > + (&(pa_to_pmdp(pa)->pv_lock))
> > +#else
> > #define pa_to_pvh(pa) (&pv_table[pa_index(pa)])
> >
> > #define NPV_LIST_LOCKS MAXCPU
> >
> > #define PHYS_TO_PV_LIST_LOCK(pa) \
> > (&pv_list_locks[pa_index(pa) % NPV_LIST_LOCKS])
> > +#endif
> >
> > #define CHANGE_PV_LIST_LOCK_TO_PHYS(lockp, pa) do { \
> > struct rwlock **_lockp = (lockp); \
> > @@ -400,14 +412,22 @@ static int pmap_initialized;
> >
> > /*
> > * Data for the pv entry allocation mechanism.
> > - * Updates to pv_invl_gen are protected by the pv_list_locks[]
> > - * elements, but reads are not.
> > + * Updates to pv_invl_gen are protected by the pv list lock but reads are
> no
> > t.
> > */
> > static TAILQ_HEAD(pch, pv_chunk) pv_chunks = TAILQ_HEAD_INITIALIZER(pv_chu
> nk
> > s);
> > static struct mtx __exclusive_cache_line pv_chunks_mutex;
> > +#if VM_NRESERVLEVEL > 0
> > +struct pmap_large_md_page {
> > + struct rwlock pv_lock;
> > + struct md_page pv_page;
> > + u_long pv_invl_gen;
> > +};
> > +static struct pmap_large_md_page *pv_table;
> > +#else
> > static struct rwlock __exclusive_cache_line pv_list_locks[NPV_LIST_LOCKS];
> > static u_long pv_invl_gen[NPV_LIST_LOCKS];
> > static struct md_page *pv_table;
> > +#endif
> > static struct md_page pv_dummy;
> >
> > /*
> > @@ -918,12 +938,21 @@ SYSCTL_LONG(_vm_pmap, OID_AUTO, invl_wait_slow, CTLFL
> A
> > "Number of slow invalidation waits for lockless DI");
> > #endif
> >
> > +#if VM_NRESERVLEVEL > 0
> > static u_long *
> > pmap_delayed_invl_genp(vm_page_t m)
> > {
> >
> > + return (&pa_to_pmdp(VM_PAGE_TO_PHYS(m))->pv_invl_gen);
> > +}
> > +#else
> > +static u_long *
> > +pmap_delayed_invl_genp(vm_page_t m)
> > +{
> > +
> > return (&pv_invl_gen[pa_index(VM_PAGE_TO_PHYS(m)) % NPV_LIST_LOCKS]);
> > }
> > +#endif
> >
> > static void
> > pmap_delayed_invl_callout_func(void *arg __unused)
> > @@ -1803,6 +1832,112 @@ pmap_page_init(vm_page_t m)
> > m->md.pat_mode = PAT_WRITE_BACK;
> > }
> >
> > +#if VM_NRESERVLEVEL > 0
> > +static void
> > +pmap_init_pv_table(void)
> > +{
> > + struct pmap_large_md_page *pvd;
> > + vm_size_t s;
> > + long start, end, highest, pv_npg;
> > + int domain, i, j, pages;
> > +
> > + /*
> > + * We strongly depend on the size being a power of two, so the assert
> > + * is overzealous. However, should the struct be resized to a
> > + * different power of two, the code below needs to be revisited.
> > + */
> > + CTASSERT((sizeof(*pvd) == 64));
> > +
> > + /*
> > + * Calculate the size of the array.
> > + */
> > + pv_npg = howmany(vm_phys_segs[vm_phys_nsegs - 1].end, NBPDR);
> > + s = (vm_size_t)pv_npg * sizeof(struct pmap_large_md_page);
> > + s = round_page(s);
> > + pv_table = (struct pmap_large_md_page *)kva_alloc(s);
> > + if (pv_table == NULL)
> > + panic("%s: kva_alloc failed\n", __func__);
> > +
> > + /*
> > + * Iterate physical segments to allocate space for respective pages.
> > + */
> > + highest = -1;
> > + s = 0;
> > + for (i = 0; i < vm_phys_nsegs; i++) {
> > + start = vm_phys_segs[i].start / NBPDR;
> > + end = vm_phys_segs[i].end / NBPDR;
> > + domain = vm_phys_segs[i].domain;
> > +
> > + if (highest >= end)
> > + continue;
> > +
> > + if (start < highest) {
> > + start = highest + 1;
> > + pvd = &pv_table[start];
> > + } else {
> > + /*
> > + * The lowest address may land somewhere in the middle
> > + * of our page. Simplify the code by pretending it is
> > + * at the beginning.
> > + */
> > + pvd = pa_to_pmdp(vm_phys_segs[i].start);
> > + pvd = (struct pmap_large_md_page *)trunc_page(pvd);
> > + start = pvd - pv_table;
> > + }
> > +
> > + pages = end - start + 1;
> > + s = round_page(pages * sizeof(*pvd));
> > + highest = start + (s / sizeof(*pvd)) - 1;
> > +
> > + for (j = 0; j < s; j += PAGE_SIZE) {
> > + vm_page_t m = vm_page_alloc_domain(NULL, 0,
> > + domain, VM_ALLOC_NORMAL | VM_ALLOC_NOOBJ);
> > + if (m == NULL)
> > + panic("vm_page_alloc_domain failed for %lx\n",
> > (vm_offset_t)pvd + j);
> > + pmap_qenter((vm_offset_t)pvd + j, &m, 1);
> > + }
> > +
> > + for (j = 0; j < s / sizeof(*pvd); j++) {
> > + rw_init_flags(&pvd->pv_lock, "pmap pv list", RW_NEW);
> > + TAILQ_INIT(&pvd->pv_page.pv_list);
> > + pvd->pv_page.pv_gen = 0;
> > + pvd->pv_page.pat_mode = 0;
> > + pvd->pv_invl_gen = 0;
> > + pvd++;
> > + }
> > + }
> > + TAILQ_INIT(&pv_dummy.pv_list);
> > +}
> > +#else
> > +static void
> > +pmap_init_pv_table(void)
> > +{
> > + vm_size_t s;
> > + long i, pv_npg;
> > +
> > + /*
> > + * Initialize the pool of pv list locks.
> > + */
> > + for (i = 0; i < NPV_LIST_LOCKS; i++)
> > + rw_init(&pv_list_locks[i], "pmap pv list");
> > +
> > + /*
> > + * Calculate the size of the pv head table for superpages.
> > + */
> > + pv_npg = howmany(vm_phys_segs[vm_phys_nsegs - 1].end, NBPDR);
> > +
> > + /*
> > + * Allocate memory for the pv head table for superpages.
> > + */
> > + s = (vm_size_t)pv_npg * sizeof(struct md_page);
> > + s = round_page(s);
> > + pv_table = (struct md_page *)kmem_malloc(s, M_WAITOK | M_ZERO);
> > + for (i = 0; i < pv_npg; i++)
> > + TAILQ_INIT(&pv_table[i].pv_list);
> > + TAILQ_INIT(&pv_dummy.pv_list);
> > +}
> > +#endif
> > +
> > /*
> > * Initialize the pmap module.
> > * Called by vm_init, to initialize any structures that the pmap
> > @@ -1813,8 +1948,7 @@ pmap_init(void)
> > {
> > struct pmap_preinit_mapping *ppim;
> > vm_page_t m, mpte;
> > - vm_size_t s;
> > - int error, i, pv_npg, ret, skz63;
> > + int error, i, ret, skz63;
> >
> > /* L1TF, reserve page @0 unconditionally */
> > vm_page_blacklist_add(0, bootverbose);
> > @@ -1902,26 +2036,7 @@ pmap_init(void)
> > */
> > mtx_init(&pv_chunks_mutex, "pmap pv chunk list", NULL, MTX_DEF);
> >
> > - /*
> > - * Initialize the pool of pv list locks.
> > - */
> > - for (i = 0; i < NPV_LIST_LOCKS; i++)
> > - rw_init(&pv_list_locks[i], "pmap pv list");
> > -
> > - /*
> > - * Calculate the size of the pv head table for superpages.
> > - */
> > - pv_npg = howmany(vm_phys_segs[vm_phys_nsegs - 1].end, NBPDR);
> > -
> > - /*
> > - * Allocate memory for the pv head table for superpages.
> > - */
> > - s = (vm_size_t)(pv_npg * sizeof(struct md_page));
> > - s = round_page(s);
> > - pv_table = (struct md_page *)kmem_malloc(s, M_WAITOK | M_ZERO);
> > - for (i = 0; i < pv_npg; i++)
> > - TAILQ_INIT(&pv_table[i].pv_list);
> > - TAILQ_INIT(&pv_dummy.pv_list);
> > + pmap_init_pv_table();
> >
> > pmap_initialized = 1;
> > for (i = 0; i < PMAP_PREINIT_MAPPING_COUNT; i++) {
> >
>
> This causes a page fault during X (xdm) startup, which loads
> drm-current-kmod.
>
> db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame
> 0xfffffe0093e9c260
> vpanic() at vpanic+0x19d/frame 0xfffffe0093e9c2b0
> panic() at panic+0x43/frame 0xfffffe0093e9c310
> vm_fault() at vm_fault+0x2126/frame 0xfffffe0093e9c460
> vm_fault_trap() at vm_fault_trap+0x73/frame 0xfffffe0093e9c4b0
> trap_pfault() at trap_pfault+0x1b6/frame 0xfffffe0093e9c510
> trap() at trap+0x2a1/frame 0xfffffe0093e9c620
> calltrap() at calltrap+0x8/frame 0xfffffe0093e9c620
> --- trap 0xc, rip = 0xffffffff80a054b1, rsp = 0xfffffe0093e9c6f0, rbp =
> 0xfffffe0093e9c7a0 ---
> pmap_enter() at pmap_enter+0x861/frame 0xfffffe0093e9c7a0
> vm_fault() at vm_fault+0x1c69/frame 0xfffffe0093e9c8f0
> vm_fault_trap() at vm_fault_trap+0x73/frame 0xfffffe0093e9c940
> trap_pfault() at trap_pfault+0x1b6/frame 0xfffffe0093e9c9a0
> trap() at trap+0x438/frame 0xfffffe0093e9cab0
> calltrap() at calltrap+0x8/frame 0xfffffe0093e9cab0
> --- trap 0xc, rip = 0x30e2a9c3, rsp = 0x7fffffffea50, rbp = 0x7fffffffeaa0
> ---
> Uptime: 3m33s
> Dumping 945 out of 7974 MB:..2%..11%..21%..31%..41%..51%..61%..72%..82%..92%
>
> (kgdb) bt
> #0 doadump (textdump=1) at pcpu_aux.h:55
> #1 0xffffffff8068c5ed in kern_reboot (howto=260)
> at /opt/src/svn-current/sys/kern/kern_shutdown.c:479
> #2 0xffffffff8068caa9 in vpanic (fmt=<value optimized out>,
> ap=<value optimized out>)
> at /opt/src/svn-current/sys/kern/kern_shutdown.c:908
> #3 0xffffffff8068c8a3 in panic (fmt=<value optimized out>)
> at /opt/src/svn-current/sys/kern/kern_shutdown.c:835
> #4 0xffffffff8098c966 in vm_fault (map=<value optimized out>,
> vaddr=<value optimized out>, fault_type=<value optimized out>,
> fault_flags=<value optimized out>, m_hold=<value optimized out>)
> at /opt/src/svn-current/sys/vm/vm_fault.c:672
> #5 0xffffffff8098a723 in vm_fault_trap (map=0xfffff80002001000,
> vaddr=<value optimized out>, fault_type=2 '\002',
> fault_flags=<value optimized out>, signo=0x0, ucode=0x0)
> at /opt/src/svn-current/sys/vm/vm_fault.c:568
> #6 0xffffffff80a18326 in trap_pfault (frame=0xfffffe0093e9c630,
> signo=<value optimized out>, ucode=<value optimized out>)
> at /opt/src/svn-current/sys/amd64/amd64/trap.c:828
> #7 0xffffffff80a177f1 in trap (frame=0xfffffe0093e9c630)
> at /opt/src/svn-current/sys/amd64/amd64/trap.c:407
> #8 0xffffffff809f1aac in calltrap ()
> at /opt/src/svn-current/sys/amd64/amd64/exception.S:289
> ---Type <return> to continue, or q <return> to quit---
> #9 0xffffffff80a054b1 in pmap_enter (pmap=<value optimized out>,
> va=851443712, m=0xfffffe0005b25ce8, prot=<value optimized out>,
> flags=2677542912, psind=<value optimized out>) at atomic.h:221
> #10 0xffffffff8098c4a9 in vm_fault (map=<value optimized out>,
> vaddr=<value optimized out>, fault_type=232 '\ufffd',
> fault_flags=<value optimized out>, m_hold=0x0)
> at /opt/src/svn-current/sys/vm/vm_fault.c:489
> #11 0xffffffff8098a723 in vm_fault_trap (map=0xfffff80173eb5000,
> vaddr=<value optimized out>, fault_type=2 '\002',
> fault_flags=<value optimized out>, signo=0xfffffe0093e9ca84,
> ucode=0xfffffe0093e9ca80) at /opt/src/svn-current/sys/vm/vm_fault.c:568
> #12 0xffffffff80a18326 in trap_pfault (frame=0xfffffe0093e9cac0,
> signo=<value optimized out>, ucode=<value optimized out>)
> at /opt/src/svn-current/sys/amd64/amd64/trap.c:828
> #13 0xffffffff80a17988 in trap (frame=0xfffffe0093e9cac0)
> at /opt/src/svn-current/sys/amd64/amd64/trap.c:347
> #14 0xffffffff809f1aac in calltrap ()
> at /opt/src/svn-current/sys/amd64/amd64/exception.S:289
> #15 0x0000000030e2a9c3 in ?? ()
> Previous frame inner to this frame (corrupt stack?)
> Current language: auto; currently minimal
> (kgdb) frame 9
> #9 0xffffffff80a054b1 in pmap_enter (pmap=<value optimized out>,
> va=851443712, m=0xfffffe0005b25ce8, prot=<value optimized out>,
> flags=2677542912, psind=<value optimized out>) at atomic.h:221
> 221 ATOMIC_CMPSET(long);
> (kgdb) l
> 216 }
> 217
> 218 ATOMIC_CMPSET(char);
> 219 ATOMIC_CMPSET(short);
> 220 ATOMIC_CMPSET(int);
> 221 ATOMIC_CMPSET(long);
> 222
> 223 /*
> 224 * Atomically add the value of v to the integer pointed to by p and
> return
> 225 * the previous value of *p.
> (kgdb)
I should use kgdb from ports instead of /usr/libexec version. Similar
result.
<4>WARN_ON(!mutex_is_locked(&fbc->lock))WARN_ON(!mutex_is_locked(&fbc->
lock))
panic: vm_fault: fault on nofault entry, addr: 0xfffffe000e01c000
cpuid = 1
time = 1570417211
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame
0xfffffe0093e9c260
vpanic() at vpanic+0x19d/frame 0xfffffe0093e9c2b0
panic() at panic+0x43/frame 0xfffffe0093e9c310
vm_fault() at vm_fault+0x2126/frame 0xfffffe0093e9c460
vm_fault_trap() at vm_fault_trap+0x73/frame 0xfffffe0093e9c4b0
trap_pfault() at trap_pfault+0x1b6/frame 0xfffffe0093e9c510
trap() at trap+0x2a1/frame 0xfffffe0093e9c620
calltrap() at calltrap+0x8/frame 0xfffffe0093e9c620
--- trap 0xc, rip = 0xffffffff80a054b1, rsp = 0xfffffe0093e9c6f0, rbp =
0xfffffe0093e9c7a0 ---
pmap_enter() at pmap_enter+0x861/frame 0xfffffe0093e9c7a0
vm_fault() at vm_fault+0x1c69/frame 0xfffffe0093e9c8f0
vm_fault_trap() at vm_fault_trap+0x73/frame 0xfffffe0093e9c940
trap_pfault() at trap_pfault+0x1b6/frame 0xfffffe0093e9c9a0
trap() at trap+0x438/frame 0xfffffe0093e9cab0
calltrap() at calltrap+0x8/frame 0xfffffe0093e9cab0
--- trap 0xc, rip = 0x30e2a9c3, rsp = 0x7fffffffea50, rbp = 0x7fffffffeaa0
---
Uptime: 3m33s
Dumping 945 out of 7974 MB:..2%..11%..21%..31%..41%..51%..61%..72%..82%..92%
__curthread () at /opt/src/svn-current/sys/amd64/include/pcpu_aux.h:55
55 __asm("movq %%gs:%P1,%0" : "=r" (td) : "n" (offsetof(struct
pcpu,
(kgdb)
Backtrace stopped: Cannot access memory at address 0x7fffffffea50
(kgdb) frame 10
#10 0xffffffff80a054b1 in atomic_fcmpset_long (dst=<optimized out>,
src=<optimized out>, expect=<optimized out>)
at /opt/src/svn-current/sys/amd64/include/atomic.h:221
221 ATOMIC_CMPSET(long);
(kgdb) l
216 }
217
218 ATOMIC_CMPSET(char);
219 ATOMIC_CMPSET(short);
220 ATOMIC_CMPSET(int);
221 ATOMIC_CMPSET(long);
222
223 /*
224 * Atomically add the value of v to the integer pointed to by p and
return
225 * the previous value of *p.
(kgdb)
--
Cheers,
Cy Schubert <cy.schub...@cschubert.com>
FreeBSD UNIX: <c...@freebsd.org> Web: http://www.FreeBSD.org
The need of the many outweighs the greed of the few.
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