[PATCH] More random map fixes
Several optimizations and fixes:
- Add ->last_free_lookup as a cache for get_next_free_offset(). No point
in iterating known full blocks.
- Reduce number of random loops to 5 for random map lookups, fallback to
next free block instead of wasting cpu cycles. Was 50.
- get_next_free_block() needs to take file offset into account.
- Reverse order of retrieving buflen and offset, so we can trim
and mark properly.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/io_u.c b/io_u.c
index 31f75cd..34c7e6f 100644
--- a/io_u.c
+++ b/io_u.c
@@ -30,10 +30,13 @@
unsigned int min_bs = td->rw_min_bs;
unsigned long long block;
unsigned int blocks;
+ unsigned int nr_blocks;
block = io_u->offset / (unsigned long long) min_bs;
blocks = 0;
- while (blocks < ((io_u->buflen + min_bs - 1) / min_bs)) {
+ nr_blocks = (io_u->buflen + min_bs - 1) / min_bs;
+
+ while (blocks < nr_blocks) {
unsigned int idx, bit;
if (!random_map_free(td, f, block))
@@ -61,11 +64,12 @@
{
int i;
- *b = 0;
- i = 0;
+ i = f->last_free_lookup;
+ *b = (i * BLOCKS_PER_MAP);
while ((*b) * td->rw_min_bs < f->real_file_size) {
if (f->file_map[i] != -1UL) {
*b += ffz(f->file_map[i]);
+ f->last_free_lookup = i;
return 0;
}
@@ -82,14 +86,15 @@
* the last io issued.
*/
static int get_next_offset(struct thread_data *td, struct fio_file *f,
- unsigned long long *offset, int ddir)
+ struct io_u *io_u)
{
+ const int ddir = io_u->ddir;
unsigned long long b, rb;
long r;
if (!td->sequential) {
unsigned long long max_blocks = f->file_size / td->min_bs[ddir];
- int loops = 50;
+ int loops = 5;
do {
r = os_random_long(&td->random_state);
@@ -103,12 +108,14 @@
if (!loops) {
if (get_next_free_block(td, f, &b))
return 1;
+
+ b += f->file_offset / td->min_bs[ddir];
}
} else
b = f->last_pos / td->min_bs[ddir];
- *offset = (b * td->min_bs[ddir]) + f->file_offset;
- if (*offset > f->real_file_size)
+ io_u->offset = (b * td->min_bs[ddir]) + f->file_offset;
+ if (io_u->offset > f->real_file_size)
return 1;
return 0;
@@ -208,11 +215,19 @@
io_u->ddir = get_rw_ddir(td);
/*
- * No log, let the seq/rand engine retrieve the next position.
+ * No log, let the seq/rand engine retrieve the next buflen and
+ * position.
*/
- if (!get_next_offset(td, f, &io_u->offset, io_u->ddir)) {
- io_u->buflen = get_next_buflen(td, io_u->ddir);
- if (io_u->buflen) {
+ io_u->buflen = get_next_buflen(td, io_u->ddir);
+ if (io_u->buflen) {
+ if (!get_next_offset(td, f, io_u)) {
+ /*
+ * mark entry before potentially trimming io_u
+ */
+ if (!td->read_iolog && !td->sequential &&
+ !td->norandommap)
+ mark_random_map(td, f, io_u);
+
/*
* If using a write iolog, store this entry.
*/
@@ -308,9 +323,6 @@
return NULL;
}
- if (!td->read_iolog && !td->sequential && !td->norandommap)
- mark_random_map(td, f, io_u);
-
f->last_pos += io_u->buflen;
if (td->verify != VERIFY_NONE)