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/*-
* Copyright (c) 2008-2014 WiredTiger, Inc.
* All rights reserved.
*
* See the file LICENSE for redistribution information.
*/
#include "wt_internal.h"
static int __block_dump_avail(WT_SESSION_IMPL *, WT_BLOCK *);
/*
* __wt_block_compact_start --
* Start compaction of a file.
*/
int
__wt_block_compact_start(WT_SESSION_IMPL *session, WT_BLOCK *block)
{
WT_UNUSED(session);
/*
* Save the current allocation plan, switch to first-fit allocation.
* We don't need the lock, but it's not a performance question and
* might avoid bugs in the future.
*/
__wt_spin_lock(session, &block->live_lock);
block->allocfirst_save = block->allocfirst;
block->allocfirst = 1;
__wt_spin_unlock(session, &block->live_lock);
return (0);
}
/*
* __wt_block_compact_end --
* End compaction of a file.
*/
int
__wt_block_compact_end(WT_SESSION_IMPL *session, WT_BLOCK *block)
{
WT_UNUSED(session);
/*
* Restore the previous allocation plan.
* We don't need the lock, but it's not a performance question and
* might avoid bugs in the future.
*/
__wt_spin_lock(session, &block->live_lock);
block->allocfirst = block->allocfirst_save;
__wt_spin_unlock(session, &block->live_lock);
return (0);
}
/*
* __wt_block_compact_skip --
* Return if compaction will shrink the file.
*/
int
__wt_block_compact_skip(WT_SESSION_IMPL *session, WT_BLOCK *block, int *skipp)
{
WT_DECL_RET;
WT_EXT *ext;
WT_EXTLIST *el;
WT_FH *fh;
off_t avail, ninety;
*skipp = 1; /* Return a default skip. */
fh = block->fh;
/*
* We do compaction by copying blocks from the end of the file to the
* beginning of the file, and we need some metrics to decide if it's
* worth doing. Ignore small files, and files where we are unlikely
* to recover 10% of the file.
*/
if (fh->size <= 10 * 1024)
return (0);
__wt_spin_lock(session, &block->live_lock);
if (WT_VERBOSE_ISSET(session, compact))
WT_ERR(__block_dump_avail(session, block));
/* Sum the number of available bytes in the first 90% of the file. */
avail = 0;
ninety = fh->size - fh->size / 10;
el = &block->live.avail;
WT_EXT_FOREACH(ext, el->off)
if (ext->off < ninety)
avail += ext->size;
/*
* If at least 10% of the total file is available and in the first 90%
* of the file, we'll try compaction.
*/
if (avail >= fh->size / 10)
*skipp = 0;
WT_VERBOSE_ERR(session, compact,
"%s: %" PRIuMAX "MB (%" PRIuMAX ") available space in the first "
"90%% of the file, require 10%% or %" PRIuMAX "MB (%" PRIuMAX
") to perform compaction, compaction %s",
block->name,
(uintmax_t)avail / WT_MEGABYTE, (uintmax_t)avail,
(uintmax_t)(fh->size / 10) / WT_MEGABYTE, (uintmax_t)fh->size / 10,
*skipp ? "skipped" : "proceeding");
err: __wt_spin_unlock(session, &block->live_lock);
return (ret);
}
/*
* __wt_block_compact_page_skip --
* Return if writing a particular page will shrink the file.
*/
int
__wt_block_compact_page_skip(WT_SESSION_IMPL *session,
WT_BLOCK *block, const uint8_t *addr, size_t addr_size, int *skipp)
{
WT_DECL_RET;
WT_EXT *ext;
WT_EXTLIST *el;
WT_FH *fh;
off_t ninety, offset;
uint32_t size, cksum;
WT_UNUSED(addr_size);
*skipp = 1; /* Return a default skip. */
fh = block->fh;
/* Crack the cookie. */
WT_RET(__wt_block_buffer_to_addr(block, addr, &offset, &size, &cksum));
__wt_spin_lock(session, &block->live_lock);
/*
* If this block is in the last 10% of the file and there's a block on
* the available list that's in the first 90% of the file, rewrite the
* block. Checking the available list is necessary (otherwise writing
* the block would extend the file), but there's an obvious race if the
* file is sufficiently busy.
*/
ninety = fh->size - fh->size / 10;
if (offset > ninety) {
el = &block->live.avail;
WT_EXT_FOREACH(ext, el->off)
if (ext->off < ninety && ext->size >= size) {
*skipp = 0;
break;
}
}
__wt_spin_unlock(session, &block->live_lock);
return (ret);
}
/*
* __block_dump_avail --
* Dump out the avail list so we can see what compaction will look like.
*/
static int
__block_dump_avail(WT_SESSION_IMPL *session, WT_BLOCK *block)
{
WT_EXTLIST *el;
WT_EXT *ext;
off_t decile[10], percentile[100], size, v;
u_int i;
el = &block->live.avail;
size = block->fh->size;
WT_RET(__wt_verbose(
session, "file size %" PRIuMAX "MB (%" PRIuMAX ") with %" PRIuMAX
"%% space available %" PRIuMAX "MB (%" PRIuMAX ")",
(uintmax_t)size / WT_MEGABYTE, (uintmax_t)size,
((uintmax_t)el->bytes * 100) / (uintmax_t)size,
(uintmax_t)el->bytes / WT_MEGABYTE, (uintmax_t)el->bytes));
if (el->entries == 0)
return (0);
/*
* Bucket the available memory into file deciles/percentiles. Large
* pieces of memory will cross over multiple buckets, assign to the
* decile/percentile in 512B chunks.
*/
memset(decile, 0, sizeof(decile));
memset(percentile, 0, sizeof(percentile));
WT_EXT_FOREACH(ext, el->off)
for (i = 0; i < ext->size / 512; ++i) {
++decile[((ext->off + i * 512) * 10) / size];
++percentile[((ext->off + i * 512) * 100) / size];
}
#ifdef __VERBOSE_OUTPUT_PERCENTILE
for (i = 0; i < WT_ELEMENTS(percentile); ++i) {
v = percentile[i] * 512;
WT_RET(__wt_verbose(
session, "%2u%%: %12" PRIuMAX "MB, (%" PRIuMAX "B, %"
PRIuMAX "%%)",
i, (uintmax_t)v / WT_MEGABYTE, (uintmax_t)v,
(uintmax_t)((v * 100) / (off_t)el->bytes)));
}
#endif
for (i = 0; i < WT_ELEMENTS(decile); ++i) {
v = decile[i] * 512;
WT_RET(__wt_verbose(
session, "%2u%%: %12" PRIuMAX "MB, (%" PRIuMAX "B, %"
PRIuMAX "%%)",
i * 10, (uintmax_t)v / WT_MEGABYTE, (uintmax_t)v,
(uintmax_t)((v * 100) / (off_t)el->bytes)));
}
return (0);
}
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