Revision c4f675cd40d955d539180506c09515c90169b15b authored by Sergei Trofimovich on 20 May 2011, 20:20:30 UTC, committed by Chris Mason on 23 May 2011, 17:24:14 UTC
Observed as a large delay when --mixed filesystem is filled up. Test example: 1. create tiny --mixed FS: $ dd if=/dev/zero of=2G.img seek=$((2048 * 1024 * 1024 - 1)) count=1 bs=1 $ mkfs.btrfs --mixed 2G.img $ mount -oloop 2G.img /mnt/ut/ 2. Try to fill it up: $ dd if=/dev/urandom of=10M.file bs=10240 count=1024 $ seq 1 256 | while read file_no; do echo $file_no; time cp 10M.file ${file_no}.copy; done Up to '200.copy' it goes fast, but when disk fills-up each -ENOSPC message takes 3 seconds to pop-up _every_ ENOSPC (and in usermode linux it's even more: 30-60 seconds!). (Maybe, time depends on kernel's timer resolution). No IO, no CPU load, just rescheduling. Some debugging revealed busy spinning in shrink_delalloc. Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org> Reviewed-by: Josef Bacik <josef@redhat.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
1 parent 0f3b708
prio_heap.c
/*
* Simple insertion-only static-sized priority heap containing
* pointers, based on CLR, chapter 7
*/
#include <linux/slab.h>
#include <linux/prio_heap.h>
int heap_init(struct ptr_heap *heap, size_t size, gfp_t gfp_mask,
int (*gt)(void *, void *))
{
heap->ptrs = kmalloc(size, gfp_mask);
if (!heap->ptrs)
return -ENOMEM;
heap->size = 0;
heap->max = size / sizeof(void *);
heap->gt = gt;
return 0;
}
void heap_free(struct ptr_heap *heap)
{
kfree(heap->ptrs);
}
void *heap_insert(struct ptr_heap *heap, void *p)
{
void *res;
void **ptrs = heap->ptrs;
int pos;
if (heap->size < heap->max) {
/* Heap insertion */
pos = heap->size++;
while (pos > 0 && heap->gt(p, ptrs[(pos-1)/2])) {
ptrs[pos] = ptrs[(pos-1)/2];
pos = (pos-1)/2;
}
ptrs[pos] = p;
return NULL;
}
/* The heap is full, so something will have to be dropped */
/* If the new pointer is greater than the current max, drop it */
if (heap->gt(p, ptrs[0]))
return p;
/* Replace the current max and heapify */
res = ptrs[0];
ptrs[0] = p;
pos = 0;
while (1) {
int left = 2 * pos + 1;
int right = 2 * pos + 2;
int largest = pos;
if (left < heap->size && heap->gt(ptrs[left], p))
largest = left;
if (right < heap->size && heap->gt(ptrs[right], ptrs[largest]))
largest = right;
if (largest == pos)
break;
/* Push p down the heap one level and bump one up */
ptrs[pos] = ptrs[largest];
ptrs[largest] = p;
pos = largest;
}
return res;
}
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