diff options
| -rw-r--r-- | xen/common/page_alloc.c | 108 | ||||
| -rw-r--r-- | xen/include/public/xen.h | 1 |
2 files changed, 109 insertions, 0 deletions
diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c index 249bb355dd..7cb16940c8 100644 --- a/xen/common/page_alloc.c +++ b/xen/common/page_alloc.c @@ -35,6 +35,7 @@ #include <xen/perfc.h> #include <xen/numa.h> #include <xen/nodemask.h> +#include <xen/event.h> #include <xen/tmem.h> #include <xen/tmem_xen.h> #include <public/sysctl.h> @@ -300,6 +301,107 @@ static unsigned long init_node_heap(int node, unsigned long mfn, return needed; } +/* Default to 64 MiB */ +#define DEFAULT_LOW_MEM_VIRQ (((paddr_t) 64) << 20) +#define MAX_LOW_MEM_VIRQ (((paddr_t) 1024) << 20) + +static paddr_t __read_mostly opt_low_mem_virq = ((paddr_t) -1); +size_param("low_mem_virq_limit", opt_low_mem_virq); + +/* Thresholds to control hysteresis. In pages */ +/* When memory grows above this threshold, reset hysteresis. + * -1 initially to not reset until at least one virq issued. */ +static unsigned long low_mem_virq_high = -1UL; +/* Threshold at which we issue virq */ +static unsigned long low_mem_virq_th = 0; +/* Original threshold after all checks completed */ +static unsigned long low_mem_virq_orig = 0; +/* Order for current threshold */ +static unsigned int low_mem_virq_th_order = 0; + +/* Perform bootstrapping checks and set bounds */ +static void __init setup_low_mem_virq(void) +{ + unsigned int order; + paddr_t threshold; + bool_t halve; + + /* If the user specifies zero, then he/she doesn't want this virq + * to ever trigger. */ + if ( opt_low_mem_virq == 0 ) + { + low_mem_virq_th = -1UL; + return; + } + + /* If the user did not specify a knob, remember that */ + halve = (opt_low_mem_virq == ((paddr_t) -1)); + threshold = halve ? DEFAULT_LOW_MEM_VIRQ : opt_low_mem_virq; + + /* Dom0 has already been allocated by now. So check we won't be + * complaining immediately with whatever's left of the heap. */ + threshold = min(threshold, + ((paddr_t) total_avail_pages) << PAGE_SHIFT); + + /* Then, cap to some predefined maximum */ + threshold = min(threshold, MAX_LOW_MEM_VIRQ); + + /* If the user specified no knob, and we are at the current available + * level, halve the threshold. */ + if ( halve && + (threshold == (((paddr_t) total_avail_pages) << PAGE_SHIFT)) ) + threshold >>= 1; + + /* Zero? Have to fire immediately */ + threshold = max(threshold, (paddr_t) PAGE_SIZE); + + /* Threshold bytes -> pages */ + low_mem_virq_th = threshold >> PAGE_SHIFT; + + /* Next, round the threshold down to the next order */ + order = get_order_from_pages(low_mem_virq_th); + if ( (1UL << order) > low_mem_virq_th ) + order--; + + /* Set bounds, ready to go */ + low_mem_virq_th = low_mem_virq_orig = 1UL << order; + low_mem_virq_th_order = order; + + printk("Initial low memory virq threshold set at 0x%lx pages.\n", + low_mem_virq_th); +} + +static void check_low_mem_virq(void) +{ + if ( unlikely(total_avail_pages <= low_mem_virq_th) ) + { + send_global_virq(VIRQ_ENOMEM); + + /* Update thresholds. Next warning will be when we drop below + * next order. However, we wait until we grow beyond one + * order above us to complain again at the current order */ + low_mem_virq_high = 1UL << (low_mem_virq_th_order + 1); + if ( low_mem_virq_th_order > 0 ) + low_mem_virq_th_order--; + low_mem_virq_th = 1UL << low_mem_virq_th_order; + return; + } + + if ( unlikely(total_avail_pages >= low_mem_virq_high) ) + { + /* Reset hysteresis. Bring threshold up one order. + * If we are back where originally set, set high + * threshold to -1 to avoid further growth of + * virq threshold. */ + low_mem_virq_th_order++; + low_mem_virq_th = 1UL << low_mem_virq_th_order; + if ( low_mem_virq_th == low_mem_virq_orig ) + low_mem_virq_high = -1UL; + else + low_mem_virq_high = 1UL << (low_mem_virq_th_order + 2); + } +} + /* Allocate 2^@order contiguous pages. */ static struct page_info *alloc_heap_pages( unsigned int zone_lo, unsigned int zone_hi, @@ -420,6 +522,8 @@ static struct page_info *alloc_heap_pages( total_avail_pages -= request; ASSERT(total_avail_pages >= 0); + check_low_mem_virq(); + if ( d != NULL ) d->last_alloc_node = node; @@ -1022,6 +1126,10 @@ void __init scrub_heap_pages(void) } printk("done.\n"); + + /* Now that the heap is initialized, run checks and set bounds + * for the low mem virq algorithm. */ + setup_low_mem_virq(); } diff --git a/xen/include/public/xen.h b/xen/include/public/xen.h index 041ad0be33..b2f6c507b9 100644 --- a/xen/include/public/xen.h +++ b/xen/include/public/xen.h @@ -158,6 +158,7 @@ DEFINE_XEN_GUEST_HANDLE(xen_pfn_t); #define VIRQ_PCPU_STATE 9 /* G. (DOM0) PCPU state changed */ #define VIRQ_MEM_EVENT 10 /* G. (DOM0) A memory event has occured */ #define VIRQ_XC_RESERVED 11 /* G. Reserved for XenClient */ +#define VIRQ_ENOMEM 12 /* G. (DOM0) Low on heap memory */ /* Architecture-specific VIRQ definitions. */ #define VIRQ_ARCH_0 16 |