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Create a knob, kern.ipc.sfreadahead, that allows one to tune the amount of

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readahead that sendfile() will do.  Default remains the same.

Obtained from:	Netflix
MFC after:	3 days
This commit is contained in:
Scott Long 2013-07-30 23:26:05 +00:00
parent ce779f3756
commit fc4a5f052b
3 changed files with 28 additions and 9 deletions
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20
sys/kern/kern_mutex.c
View File

@ -218,13 +218,14 @@ __mtx_lock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
file, line));
WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
file, line, NULL);
WITNESS_CHECKORDER(&m->lock_object, (opts & ~MTX_RECURSE) |
LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
__mtx_lock(m, curthread, opts, file, line);
LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
line);
WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
WITNESS_LOCK(&m->lock_object, (opts & ~MTX_RECURSE) | LOP_EXCLUSIVE,
file, line);
curthread->td_locks++;
}
@ -271,9 +272,11 @@ __mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
("mtx_lock_spin() of sleep mutex %s @ %s:%d",
m->lock_object.lo_name, file, line));
if (mtx_owned(m))
KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
(opts & MTX_RECURSE) != 0,
("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n",
m->lock_object.lo_name, file, line));
opts &= ~MTX_RECURSE;
WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
file, line, NULL);
__mtx_lock_spin(m, curthread, opts, file, line);
@ -335,12 +338,14 @@ _mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line)
("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
file, line));
if (mtx_owned(m) && (m->lock_object.lo_flags & LO_RECURSABLE) != 0) {
if (mtx_owned(m) && ((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
(opts & MTX_RECURSE) != 0)) {
m->mtx_recurse++;
atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
rval = 1;
} else
rval = _mtx_obtain_lock(m, (uintptr_t)curthread);
opts &= ~MTX_RECURSE;
LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line);
if (rval) {
@ -391,15 +396,18 @@ __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t tid, int opts,
m = mtxlock2mtx(c);
if (mtx_owned(m)) {
KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
(opts & MTX_RECURSE) != 0,
("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n",
m->lock_object.lo_name, file, line));
opts &= ~MTX_RECURSE;
m->mtx_recurse++;
atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
if (LOCK_LOG_TEST(&m->lock_object, opts))
CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m);
return;
}
opts &= ~MTX_RECURSE;
#ifdef HWPMC_HOOKS
PMC_SOFT_CALL( , , lock, failed);

8
sys/kern/subr_uio.c
View File

@ -56,6 +56,7 @@ __FBSDID("$FreeBSD$");
#include <vm/vm_param.h>
#include <vm/vm_extern.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_map.h>
#ifdef SOCKET_SEND_COW
#include <vm/vm_object.h>
@ -122,7 +123,12 @@ vm_pgmoveco(vm_map_t mapa, vm_offset_t kaddr, vm_offset_t uaddr)
if (uobject->backing_object != NULL)
pmap_remove(map->pmap, uaddr, uaddr + PAGE_SIZE);
}
vm_page_insert(kern_pg, uobject, upindex);
if (vm_page_insert(kern_pg, uobject, upindex)) {
VM_OBJECT_WUNLOCK(uobject);
VM_WAIT;
VM_OBJECT_WLOCK(uobject);
goto retry;
}
vm_page_dirty(kern_pg);
VM_OBJECT_WUNLOCK(uobject);
vm_map_lookup_done(map, entry);

9
sys/kern/uipc_syscalls.c
View File

@ -122,6 +122,7 @@ counter_u64_t sfstat[sizeof(struct sfstat) / sizeof(uint64_t)];
int nsfbufs;
int nsfbufspeak;
int nsfbufsused;
static int sfreadahead = MAXPHYS / MAXBSIZE;
SYSCTL_INT(_kern_ipc, OID_AUTO, nsfbufs, CTLFLAG_RDTUN, &nsfbufs, 0,
"Maximum number of sendfile(2) sf_bufs available");
@ -129,6 +130,9 @@ SYSCTL_INT(_kern_ipc, OID_AUTO, nsfbufspeak, CTLFLAG_RD, &nsfbufspeak, 0,
"Number of sendfile(2) sf_bufs at peak usage");
SYSCTL_INT(_kern_ipc, OID_AUTO, nsfbufsused, CTLFLAG_RD, &nsfbufsused, 0,
"Number of sendfile(2) sf_bufs in use");
SYSCTL_INT(_kern_ipc, OID_AUTO, sfreadahead, CTLFLAG_RW, &sfreadahead, 0,
"Number of sendfile(2) read-ahead MAXBSIZE blocks");
static void
sfstat_init(const void *unused)
@ -2240,6 +2244,7 @@ kern_sendfile(struct thread *td, struct sendfile_args *uap,
error = EBUSY;
else {
ssize_t resid;
int readahead = sfreadahead * MAXBSIZE;
/*
* Ensure that our page is still around
@ -2255,9 +2260,9 @@ kern_sendfile(struct thread *td, struct sendfile_args *uap,
* wrong, but is consistent with our original
* implementation.
*/
error = vn_rdwr(UIO_READ, vp, NULL, MAXBSIZE,
error = vn_rdwr(UIO_READ, vp, NULL, readahead,
trunc_page(off), UIO_NOCOPY, IO_NODELOCKED |
IO_VMIO | ((MAXBSIZE / bsize) << IO_SEQSHIFT),
IO_VMIO | ((readahead / bsize) << IO_SEQSHIFT),
td->td_ucred, NOCRED, &resid, td);
VM_OBJECT_WLOCK(obj);
vm_page_io_finish(pg);