/*
* p->p_token is held on entry.
*/
static int
procfs_rwmem(struct proc *curp, struct proc *p, struct uio *uio)
{
int error;
int writing;
struct vmspace *vm;
vm_map_t map;
vm_offset_t pageno = 0; /* page number */
vm_prot_t reqprot;
vm_offset_t kva;
/*
* if the vmspace is in the midst of being allocated or deallocated,
* or the process is exiting, don't try to grab anything. The
* page table usage in that process may be messed up.
*/
vm = p->p_vmspace;
if (p->p_stat == SIDL || p->p_stat == SZOMB)
return EFAULT;
if ((p->p_flags & (P_WEXIT | P_INEXEC)) ||
sysref_isinactive(&vm->vm_sysref))
return EFAULT;
/*
* The map we want...
*/
vmspace_hold(vm);
map = &vm->vm_map;
writing = (uio->uio_rw == UIO_WRITE);
reqprot = VM_PROT_READ;
if (writing)
reqprot |= VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE;
kva = kmem_alloc_pageable(&kernel_map, PAGE_SIZE);
/*
* Only map in one page at a time. We don't have to, but it
* makes things easier. This way is trivial - right?
*/
do {
vm_offset_t uva;
vm_offset_t page_offset; /* offset into page */
size_t len;
vm_page_t m;
uva = (vm_offset_t) uio->uio_offset;
/*
* Get the page number of this segment.
*/
pageno = trunc_page(uva);
page_offset = uva - pageno;
/*
* How many bytes to copy
*/
len = szmin(PAGE_SIZE - page_offset, uio->uio_resid);
/*
* Fault the page on behalf of the process
*/
m = vm_fault_page(map, pageno, reqprot,
VM_FAULT_NORMAL, &error);
if (error) {
KKASSERT(m == NULL);
error = EFAULT;
break;
}
/*
* Cleanup tmap then create a temporary KVA mapping and
* do the I/O. We can switch between cpus so don't bother
* synchronizing across all cores.
*/
pmap_kenter_quick(kva, VM_PAGE_TO_PHYS(m));
error = uiomove((caddr_t)(kva + page_offset), len, uio);
pmap_kremove_quick(kva);
/*
* release the page and we are done
*/
vm_page_unhold(m);
} while (error == 0 && uio->uio_resid > 0);
vmspace_drop(vm);
kmem_free(&kernel_map, kva, PAGE_SIZE);
return (error);
}
/*
* Process only has its hold count bumped, we need the token
* to safely scan the LWPs
*/
static int
scheduler_callback(struct proc *p, void *data)
{
struct scheduler_info *info = data;
struct vmspace *vm;
struct lwp *lp;
segsz_t pgs;
int pri;
/*
* We only care about processes in swap-wait. Interlock test with
* token if the flag is found set.
*/
if ((p->p_flags & P_SWAPWAIT) == 0)
return 0;
lwkt_gettoken_shared(&p->p_token);
if ((p->p_flags & P_SWAPWAIT) == 0) {
lwkt_reltoken(&p->p_token);
return 0;
}
/*
* Calculate priority for swap-in
*/
pri = 0;
FOREACH_LWP_IN_PROC(lp, p) {
/* XXX lwp might need a different metric */
pri += lp->lwp_slptime;
}
pri += p->p_swtime - p->p_nice * 8;
/*
* The more pages paged out while we were swapped,
* the more work we have to do to get up and running
* again and the lower our wakeup priority.
*
* Each second of sleep time is worth ~1MB
*/
if ((vm = p->p_vmspace) != NULL) {
vmspace_hold(vm);
pgs = vmspace_resident_count(vm);
if (pgs < vm->vm_swrss) {
pri -= (vm->vm_swrss - pgs) /
(1024 * 1024 / PAGE_SIZE);
}
vmspace_drop(vm);
}
lwkt_reltoken(&p->p_token);
/*
* If this process is higher priority and there is
* enough space, then select this process instead of
* the previous selection.
*/
if (pri > info->ppri) {
if (info->pp)
PRELE(info->pp);
PHOLD(p);
info->pp = p;
info->ppri = pri;
}
return(0);
}
