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Subject[RFC PATCH 2/3] use hrtimer in select and pselect
This changes the select and pselect system calls to use the
new schedule_timeout_hr function. Since many applications
use the select function instead of nanosleep, this provides
a higher resolution sleep to them.

BUG: the same needs to be done for the compat syscalls, the
current patch breaks building on 64 bit machines.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Index: linux-cg/fs/select.c
===================================================================
--- linux-cg.orig/fs/select.c
+++ linux-cg/fs/select.c
@@ -189,7 +189,7 @@ get_max:
#define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR)
#define POLLEX_SET (POLLPRI)

-int do_select(int n, fd_set_bits *fds, s64 *timeout)
+int do_select(int n, fd_set_bits *fds, ktime_t *timeout)
{
struct poll_wqueues table;
poll_table *wait;
@@ -205,12 +205,11 @@ int do_select(int n, fd_set_bits *fds, s

poll_initwait(&table);
wait = &table.pt;
- if (!*timeout)
+ if (timeout && !timeout->tv64)
wait = NULL;
retval = 0;
for (;;) {
unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp;
- long __timeout;

set_current_state(TASK_INTERRUPTIBLE);

@@ -266,27 +265,19 @@ int do_select(int n, fd_set_bits *fds, s
*rexp = res_ex;
}
wait = NULL;
- if (retval || !*timeout || signal_pending(current))
+ if (retval || (timeout && !timeout->tv64)
+ || signal_pending(current))
break;
if(table.error) {
retval = table.error;
break;
}

- if (*timeout < 0) {
+ if (!timeout || timeout->tv64 < 0)
/* Wait indefinitely */
- __timeout = MAX_SCHEDULE_TIMEOUT;
- } else if (unlikely(*timeout >= (s64)MAX_SCHEDULE_TIMEOUT - 1)) {
- /* Wait for longer than MAX_SCHEDULE_TIMEOUT. Do it in a loop */
- __timeout = MAX_SCHEDULE_TIMEOUT - 1;
- *timeout -= __timeout;
- } else {
- __timeout = *timeout;
- *timeout = 0;
- }
- __timeout = schedule_timeout(__timeout);
- if (*timeout >= 0)
- *timeout += __timeout;
+ schedule();
+ else
+ *timeout = schedule_timeout_hr(*timeout);
}
__set_current_state(TASK_RUNNING);

@@ -307,7 +298,7 @@ int do_select(int n, fd_set_bits *fds, s
((unsigned long) (MAX_SCHEDULE_TIMEOUT / HZ)-1)

static int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
- fd_set __user *exp, s64 *timeout)
+ fd_set __user *exp, ktime_t *timeout)
{
fd_set_bits fds;
void *bits;
@@ -384,7 +375,7 @@ out_nofds:
asmlinkage long sys_select(int n, fd_set __user *inp, fd_set __user *outp,
fd_set __user *exp, struct timeval __user *tvp)
{
- s64 timeout = -1;
+ ktime_t timeout, *timeoutp = NULL;
struct timeval tv;
int ret;

@@ -395,24 +386,20 @@ asmlinkage long sys_select(int n, fd_set
if (tv.tv_sec < 0 || tv.tv_usec < 0)
return -EINVAL;

+ timeout = timeval_to_ktime(tv);
/* Cast to u64 to make GCC stop complaining */
- if ((u64)tv.tv_sec >= (u64)MAX_INT64_SECONDS)
- timeout = -1; /* infinite */
- else {
- timeout = ROUND_UP(tv.tv_usec, USEC_PER_SEC/HZ);
- timeout += tv.tv_sec * HZ;
- }
+ if ((u64)tv.tv_sec < (u64)MAX_INT64_SECONDS)
+ timeoutp = &timeout;
}

- ret = core_sys_select(n, inp, outp, exp, &timeout);
+ ret = core_sys_select(n, inp, outp, exp, timeoutp);

if (tvp) {
struct timeval rtv;

if (current->personality & STICKY_TIMEOUTS)
goto sticky;
- rtv.tv_usec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ));
- rtv.tv_sec = timeout;
+ rtv = ktime_to_timeval(timeout);
if (timeval_compare(&rtv, &tv) >= 0)
rtv = tv;
if (copy_to_user(tvp, &rtv, sizeof(rtv))) {
@@ -438,7 +425,7 @@ asmlinkage long sys_pselect7(int n, fd_s
fd_set __user *exp, struct timespec __user *tsp,
const sigset_t __user *sigmask, size_t sigsetsize)
{
- s64 timeout = MAX_SCHEDULE_TIMEOUT;
+ ktime_t timeout, *timeoutp = NULL;
sigset_t ksigmask, sigsaved;
struct timespec ts;
int ret;
@@ -450,13 +437,11 @@ asmlinkage long sys_pselect7(int n, fd_s
if (ts.tv_sec < 0 || ts.tv_nsec < 0)
return -EINVAL;

+ timeout = timespec_to_ktime(ts);
+
/* Cast to u64 to make GCC stop complaining */
- if ((u64)ts.tv_sec >= (u64)MAX_INT64_SECONDS)
- timeout = -1; /* infinite */
- else {
- timeout = ROUND_UP(ts.tv_nsec, NSEC_PER_SEC/HZ);
- timeout += ts.tv_sec * HZ;
- }
+ if ((u64)ts.tv_sec < (u64)MAX_INT64_SECONDS)
+ timeoutp = &timeout;
}

if (sigmask) {
@@ -470,16 +455,15 @@ asmlinkage long sys_pselect7(int n, fd_s
sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
}

- ret = core_sys_select(n, inp, outp, exp, &timeout);
+ ret = core_sys_select(n, inp, outp, exp, timeoutp);

if (tsp) {
struct timespec rts;

if (current->personality & STICKY_TIMEOUTS)
goto sticky;
- rts.tv_nsec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)) *
- 1000;
- rts.tv_sec = timeout;
+
+ rts = ktime_to_timespec(timeout);
if (timespec_compare(&rts, &ts) >= 0)
rts = ts;
if (copy_to_user(tsp, &rts, sizeof(rts))) {
Index: linux-cg/include/linux/poll.h
===================================================================
--- linux-cg.orig/include/linux/poll.h
+++ linux-cg/include/linux/poll.h
@@ -112,7 +112,7 @@ void zero_fd_set(unsigned long nr, unsig

#define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1)

-extern int do_select(int n, fd_set_bits *fds, s64 *timeout);
+extern int do_select(int n, fd_set_bits *fds, ktime_t *timeout);
extern int do_sys_poll(struct pollfd __user * ufds, unsigned int nfds,
s64 *timeout);

--

-
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