1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
|
/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1996, 1997, 1998, 1999
* Sleepycat Software. All rights reserved.
*/
#include "db_config.h"
#ifndef lint
static const char sccsid[] = "@(#)mp_trickle.c 11.3 (Sleepycat) 9/16/99";
#endif /* not lint */
#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>
#include <errno.h>
#include <stdlib.h>
#endif
#include "db_int.h"
#include "db_shash.h"
#include "mp.h"
static int CDB___memp_trick __P((DB_ENV *, int, int, int *));
/*
* CDB_memp_trickle --
* Keep a specified percentage of the buffers clean.
*/
int
CDB_memp_trickle(dbenv, pct, nwrotep)
DB_ENV *dbenv;
int pct, *nwrotep;
{
DB_MPOOL *dbmp;
MPOOL *mp;
u_int32_t i;
int ret;
PANIC_CHECK(dbenv);
ENV_REQUIRES_CONFIG(dbenv, dbenv->mp_handle, DB_INIT_MPOOL);
dbmp = dbenv->mp_handle;
mp = dbmp->reginfo.primary;
if (nwrotep != NULL)
*nwrotep = 0;
if (pct < 1 || pct > 100)
return (EINVAL);
R_LOCK(dbenv, &dbmp->reginfo);
/* Loop through the caches... */
for (ret = 0, i = 0; i < mp->nc_reg; ++i)
if ((ret = CDB___memp_trick(dbenv, i, pct, nwrotep)) != 0)
break;
R_UNLOCK(dbenv, &dbmp->reginfo);
return (ret);
}
/*
* CDB___memp_trick --
* Trickle a single cache.
*/
static int
CDB___memp_trick(dbenv, ncache, pct, nwrotep)
DB_ENV *dbenv;
int ncache, pct, *nwrotep;
{
BH *bhp;
DB_MPOOL *dbmp;
MCACHE *mc;
MPOOLFILE *mfp;
db_pgno_t pgno;
u_long total;
int ret, wrote;
dbmp = dbenv->mp_handle;
mc = dbmp->c_reginfo[ncache].primary;
/*
* If there are sufficient clean buffers, or no buffers or no dirty
* buffers, we're done.
*
* XXX
* Using st_page_clean and st_page_dirty is our only choice at the
* moment, but it's not as correct as we might like in the presence
* of pools with more than one buffer size, as a free 512-byte buffer
* isn't the same as a free 8K buffer.
*/
loop: total = mc->stat.st_page_clean + mc->stat.st_page_dirty;
if (total == 0 || mc->stat.st_page_dirty == 0 ||
(mc->stat.st_page_clean * 100) / total >= (u_long)pct)
return (0);
/* Loop until we write a buffer. */
for (bhp = SH_TAILQ_FIRST(&mc->bhq, __bh);
bhp != NULL; bhp = SH_TAILQ_NEXT(bhp, q, __bh)) {
if (bhp->ref != 0 ||
!F_ISSET(bhp, BH_DIRTY) || F_ISSET(bhp, BH_LOCKED))
continue;
mfp = R_ADDR(&dbmp->reginfo, bhp->mf_offset);
/*
* We can't write to temporary files -- see the comment in
* mp_bh.c:CDB___memp_bhwrite().
*/
if (F_ISSET(mfp, MP_TEMP))
continue;
pgno = bhp->pgno;
if ((ret = CDB___memp_bhwrite(dbmp, mfp, bhp, NULL, &wrote)) != 0)
return (ret);
/*
* Any process syncing the shared memory buffer pool had better
* be able to write to any underlying file. Be understanding,
* but firm, on this point.
*/
if (!wrote) {
CDB___db_err(dbenv, "%s: unable to flush page: %lu",
CDB___memp_fns(dbmp, mfp), (u_long)pgno);
return (EPERM);
}
++mc->stat.st_page_trickle;
if (nwrotep != NULL)
++*nwrotep;
goto loop;
}
return (0);
}
|
