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Remove artificial restriction on lio_listio's operation count

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In r322258 I made p1003_1b.aio_listio_max a tunable. However, further
investigation shows that there was never any good reason for that limit to
exist in the first place. It's used in two completely different ways:

* To size a UMA zone, which globally limits the number of concurrent
  aio_suspend calls.

* To artifically limit the number of operations in a single lio_listio call.
  There doesn't seem to be any memory allocation associated with this limit.

This change does two things:

* Properly names aio_suspend's UMA zone, and sizes it based on a new constant.

* Eliminates the artifical restriction on lio_listio. Instead, lio_listio
  calls will now be limited by the more generous max_aio_queue_per_proc. The
  old p1003_1b.aio_listio_max is now an alias for
  vfs.aio.max_aio_queue_per_proc, so sysconf(3) will still work with
  _SC_AIO_LISTIO_MAX.

Reported by:	bde
Reviewed by:	jhb
MFC after:	3 weeks
Sponsored by:	Spectra Logic Corp
Differential Revision:	https://reviews.freebsd.org/D12120
This commit is contained in:
asomers 2017-10-23 23:12:01 +00:00
parent 010bb3a477
commit d4f614fd9c
3 changed files with 28 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
lib/libc/sys/aio_suspend.2
View File

@ -85,10 +85,10 @@ expired before any I/O requests completed.
The
.Fa iocbs
argument
contains more than
.Dv AIO_LISTIO_MAX
asynchronous I/O requests, or at least one of the requests is not
valid.
contains more asynchronous I/O requests than the
.Va vfs.aio.max_aio_queue_per_proc
.Xr sysctl 8
variable, or at least one of the requests is not valid.
.It Bq Er EINTR
the suspend was interrupted by a signal.
.El

4
lib/libc/sys/lio_listio.2
View File

@ -161,7 +161,7 @@ function will fail if:
There are not enough resources to enqueue the requests.
.It Bq Er EAGAIN
The request would cause the system-wide limit
.Dv AIO_MAX
.Dv {AIO_MAX}
to be exceeded.
.It Bq Er EINVAL
The
@ -173,7 +173,7 @@ nor
or
.Fa nent
is greater than
.Dv AIO_LISTIO_MAX .
.Dv {AIO_LISTIO_MAX} .
.It Bq Er EINVAL
The asynchronous notification method in
.Fa sig->sigev_notify

47
sys/kern/vfs_aio.c
View File

@ -90,11 +90,11 @@ static uint64_t jobseqno;
#endif
#ifndef MAX_AIO_QUEUE_PER_PROC
#define MAX_AIO_QUEUE_PER_PROC 256 /* Bigger than AIO_LISTIO_MAX */
#define MAX_AIO_QUEUE_PER_PROC 256
#endif
#ifndef MAX_AIO_QUEUE
#define MAX_AIO_QUEUE 1024 /* Bigger than AIO_LISTIO_MAX */
#define MAX_AIO_QUEUE 1024 /* Bigger than MAX_AIO_QUEUE_PER_PROC */
#endif
#ifndef MAX_BUF_AIO
@ -105,6 +105,7 @@ FEATURE(aio, "Asynchronous I/O");
SYSCTL_DECL(_p1003_1b);
static MALLOC_DEFINE(M_LIO, "lio", "listio aio control block list");
static MALLOC_DEFINE(M_AIOS, "aios", "aio_suspend aio control block list");
static SYSCTL_NODE(_vfs, OID_AUTO, aio, CTLFLAG_RW, 0,
"Async IO management");
@ -169,10 +170,14 @@ static int max_buf_aio = MAX_BUF_AIO;
SYSCTL_INT(_vfs_aio, OID_AUTO, max_buf_aio, CTLFLAG_RW, &max_buf_aio, 0,
"Maximum buf aio requests per process (stored in the process)");
static int aio_listio_max = AIO_LISTIO_MAX;
/*
* Though redundant with vfs.aio.max_aio_queue_per_proc, POSIX requires
* sysconf(3) to support AIO_LISTIO_MAX, and we implement that with
* vfs.aio.aio_listio_max.
*/
SYSCTL_INT(_p1003_1b, CTL_P1003_1B_AIO_LISTIO_MAX, aio_listio_max,
CTLFLAG_RDTUN | CTLFLAG_CAPRD, &aio_listio_max, 0,
"Maximum aio requests for a single lio_listio call");
CTLFLAG_RD | CTLFLAG_CAPRD, &max_aio_queue_per_proc,
0, "Maximum aio requests for a single lio_listio call");
#ifdef COMPAT_FREEBSD6
typedef struct oaiocb {
@ -334,10 +339,9 @@ static int filt_lio(struct knote *kn, long hint);
* kaio Per process async io info
* aiop async io process data
* aiocb async io jobs
* aiol list io job pointer - internal to aio_suspend XXX
* aiolio list io jobs
*/
static uma_zone_t kaio_zone, aiop_zone, aiocb_zone, aiol_zone, aiolio_zone;
static uma_zone_t kaio_zone, aiop_zone, aiocb_zone, aiolio_zone;
/* kqueue filters for aio */
static struct filterops aio_filtops = {
@ -394,11 +398,6 @@ static int
aio_onceonly(void)
{
if (aio_listio_max < AIO_LISTIO_MAX)
aio_listio_max = AIO_LISTIO_MAX;
if (aio_listio_max > MIN(MAX_AIO_QUEUE_PER_PROC, max_queue_count))
aio_listio_max = MIN(MAX_AIO_QUEUE_PER_PROC, max_queue_count);
exit_tag = EVENTHANDLER_REGISTER(process_exit, aio_proc_rundown, NULL,
EVENTHANDLER_PRI_ANY);
exec_tag = EVENTHANDLER_REGISTER(process_exec, aio_proc_rundown_exec,
@ -416,8 +415,6 @@ aio_onceonly(void)
NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
aiocb_zone = uma_zcreate("AIOCB", sizeof(struct kaiocb), NULL, NULL,
NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
aiol_zone = uma_zcreate("AIOL", aio_listio_max * sizeof(intptr_t) ,
NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
aiolio_zone = uma_zcreate("AIOLIO", sizeof(struct aioliojob), NULL,
NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
aiod_lifetime = AIOD_LIFETIME_DEFAULT;
@ -1953,7 +1950,7 @@ sys_aio_suspend(struct thread *td, struct aio_suspend_args *uap)
struct aiocb **ujoblist;
int error;
if (uap->nent < 0 || uap->nent > aio_listio_max)
if (uap->nent < 0 || uap->nent > max_aio_queue_per_proc)
return (EINVAL);
if (uap->timeout) {
@ -1964,11 +1961,11 @@ sys_aio_suspend(struct thread *td, struct aio_suspend_args *uap)
} else
tsp = NULL;
ujoblist = uma_zalloc(aiol_zone, M_WAITOK);
ujoblist = malloc(uap->nent * sizeof(ujoblist[0]), M_AIOS, M_WAITOK);
error = copyin(uap->aiocbp, ujoblist, uap->nent * sizeof(ujoblist[0]));
if (error == 0)
error = kern_aio_suspend(td, uap->nent, ujoblist, tsp);
uma_zfree(aiol_zone, ujoblist);
free(ujoblist, M_AIOS);
return (error);
}
@ -2161,7 +2158,7 @@ kern_lio_listio(struct thread *td, int mode, struct aiocb * const *uacb_list,
if ((mode != LIO_NOWAIT) && (mode != LIO_WAIT))
return (EINVAL);
if (nent < 0 || nent > aio_listio_max)
if (nent < 0 || nent > max_aio_queue_per_proc)
return (EINVAL);
if (p->p_aioinfo == NULL)
@ -2293,7 +2290,7 @@ freebsd6_lio_listio(struct thread *td, struct freebsd6_lio_listio_args *uap)
return (EINVAL);
nent = uap->nent;
if (nent < 0 || nent > aio_listio_max)
if (nent < 0 || nent > max_aio_queue_per_proc)
return (EINVAL);
if (uap->sig && (uap->mode == LIO_NOWAIT)) {
@ -2330,7 +2327,7 @@ sys_lio_listio(struct thread *td, struct lio_listio_args *uap)
return (EINVAL);
nent = uap->nent;
if (nent < 0 || nent > aio_listio_max)
if (nent < 0 || nent > max_aio_queue_per_proc)
return (EINVAL);
if (uap->sig && (uap->mode == LIO_NOWAIT)) {
@ -2799,7 +2796,7 @@ freebsd32_aio_suspend(struct thread *td, struct freebsd32_aio_suspend_args *uap)
uint32_t *ujoblist32;
int error, i;
if (uap->nent < 0 || uap->nent > aio_listio_max)
if (uap->nent < 0 || uap->nent > max_aio_queue_per_proc)
return (EINVAL);
if (uap->timeout) {
@ -2812,7 +2809,7 @@ freebsd32_aio_suspend(struct thread *td, struct freebsd32_aio_suspend_args *uap)
} else
tsp = NULL;
ujoblist = uma_zalloc(aiol_zone, M_WAITOK);
ujoblist = malloc(uap->nent * sizeof(ujoblist[0]), M_AIOS, M_WAITOK);
ujoblist32 = (uint32_t *)ujoblist;
error = copyin(uap->aiocbp, ujoblist32, uap->nent *
sizeof(ujoblist32[0]));
@ -2822,7 +2819,7 @@ freebsd32_aio_suspend(struct thread *td, struct freebsd32_aio_suspend_args *uap)
error = kern_aio_suspend(td, uap->nent, ujoblist, tsp);
}
uma_zfree(aiol_zone, ujoblist);
free(ujoblist, M_AIOS);
return (error);
}
@ -2925,7 +2922,7 @@ freebsd6_freebsd32_lio_listio(struct thread *td,
return (EINVAL);
nent = uap->nent;
if (nent < 0 || nent > aio_listio_max)
if (nent < 0 || nent > max_aio_queue_per_proc)
return (EINVAL);
if (uap->sig && (uap->mode == LIO_NOWAIT)) {
@ -2971,7 +2968,7 @@ freebsd32_lio_listio(struct thread *td, struct freebsd32_lio_listio_args *uap)
return (EINVAL);
nent = uap->nent;
if (nent < 0 || nent > aio_listio_max)
if (nent < 0 || nent > max_aio_queue_per_proc)
return (EINVAL);
if (uap->sig && (uap->mode == LIO_NOWAIT)) {