ref: eef0fe67ee4bb8c254f0f9e61c24ef5d34d05a4f
parent: 9073565b4482a85a72d82508adb76496975734d6
author: 9ferno <[email protected]>
date: Sun Oct 23 04:19:05 EDT 2022
implemented sync and write throttling
--- a/9p.c
+++ b/9p.c
@@ -758,7 +758,8 @@
QLock lck;
Work works[Nworks];
u16 hd, tl, nworks;
- Rendez isfull, isempty;
+ Rendez isfull; /* throttling */
+ Rendez isempty; /* workers do not have to keep polling to find work */
};
Buffer buf;
--- a/TODO
+++ b/TODO
@@ -1,6 +1,3 @@
-implement sync
-throttling when the write queue becomes too much
- show the writer queue when reading /adm/ctl
profiling
read only mode
mafswrite():
@@ -20,5 +17,3 @@
cat /adm/ctl
make docs/mafs.ms more interesting?
test -A announce
-
-prepare tests and merge chktag.c and tests/sizes.c
--- a/ctl.c
+++ b/ctl.c
@@ -98,11 +98,14 @@
free = nfrees(&frees);
used = config.nblocks - free;
+
+ n = snprint(buf, 1024, "pending writes %llud blocks\n", pendingwrites());
if(config.size > TiB)
- n = snprint(buf, 1024, "(blocks) free %ulld, used %ulld, total %ulld\n"
+ n += snprint(buf+n, 1024-n, "(blocks) free %ulld, used %ulld, total %ulld\n"
"(MiB) free %ulld, used %ulld, total %ulld\n"
"(GiB) free %ulld, used %ulld, total %ulld\n"
- "(TiB) free %ulld, used %ulld, total %ulld\n",
+ "(TiB) free %ulld, used %ulld, total %ulld\n"
+ "pending writes %llud\n",
free, used, config.nblocks,
free * Rawblocksize / MiB,
used * Rawblocksize / MiB,
@@ -112,10 +115,11 @@
config.size / GiB,
free * Rawblocksize / TiB,
used * Rawblocksize / TiB,
- config.size / TiB
+ config.size / TiB,
+ pendingwrites()
);
else if(config.size > GiB)
- n = snprint(buf, 1024, "(blocks) free %ulld, used %ulld, total %ulld\n"
+ n += snprint(buf+n, 1024-n, "(blocks) free %ulld, used %ulld, total %ulld\n"
"(MiB) free %ulld, used %ulld, total %ulld\n"
"(GiB) free %ulld, used %ulld, total %ulld\n",
free, used, config.nblocks,
@@ -127,7 +131,7 @@
config.size / GiB
);
else if(config.size > MiB)
- n = snprint(buf, 1024, "(blocks) free %ulld, used %ulld, total %ulld\n"
+ n += snprint(buf+n, 1024-n, "(blocks) free %ulld, used %ulld, total %ulld\n"
"(MiB) free %ulld, used %ulld, total %ulld\n",
free, used, config.nblocks,
free * Rawblocksize / MiB,
@@ -135,7 +139,7 @@
config.size / MiB
);
else
- n = snprint(buf, 1024, "(blocks) free %ulld, used %ulld, total %ulld\n"
+ n += snprint(buf+n, 1024-n, "(blocks) free %ulld, used %ulld, total %ulld\n"
"(KiB) free %ulld, used %ulld, total %ulld\n",
free, used, config.nblocks,
free * Rawblocksize / KiB,
--- a/dat.h
+++ b/dat.h
@@ -37,6 +37,7 @@
*/
Nbuckets = 256*KiB, /* number of Hiob */
Ncollisions = 4, /* soft limit after which we start reusing older Iobuf's */
+ Npendingwrites = MiB, /* write throttling */
/* Qpnone is the Tag.path of free blocks/extents(Tfree),
and zero'ed out dentry blocks */
--- a/docs/mafs.ms
+++ b/docs/mafs.ms
@@ -763,7 +763,8 @@
QLock lck; /* controls access to this queue */
Wbuf *head, *tail; /* linked list of dirty blocks yet to be written to the disk */
s32 n;
- Rendez isempty;
+ Rendez isfull; /* write throttling */
+ Rendez isempty; /* writer does not have to keep polling to find work */
} drts = {0};struct Wbuf
@@ -784,7 +785,9 @@
.sp
Free'd blocks are not written to the disk to avoid writing blanks to a disk.
.sp
+The writer throttles input when there are more than Npendingwrites waiting to be written. This can be adjusted with the -w parameter.
.sp
+.sp
.ne 4
.ft B
Free blocks - Extents
@@ -1226,7 +1229,7 @@
.sp
echo sync >> /n/mafs_myservice/adm/ctl
.sp
-Stop Mafs.
+Stop Mafs. This command does not return until all the writes are written to the disk. So, could take a long time if you have a long writer queue.
.sp
echo halt >> /n/mafs_myservice/adm/ctl
.sp
--- a/mafs.c
+++ b/mafs.c
@@ -19,6 +19,7 @@
u8 noauth = 0;
u8 readonly = 0;
u8 shuttingdown = 0;
+extern u64 npendingwrites; /* write throttling */
int writeallow; /* never on; for compatibility with fs */
int wstatallow;
@@ -32,7 +33,7 @@
static void
usage(void)
{- fprint(2, "usage: mafs [-Ds] [-r service] [-n service] [-h nbuckets] [-a announce-string]... fsfile\n");
+ fprint(2, "usage: mafs [-Ds] [-r service] [-n service] [-h nbuckets] [-w npendingwrites] [-a announce-string]... fsfile\n");
exits("usage");}
@@ -55,6 +56,7 @@
rfork(RFNAMEG|RFNOTEG|RFREND);
nbuckets = Nbuckets;
+ npendingwrites = Npendingwrites;
sfd = -1;
doream = stdio = netc = 0;
@@ -69,6 +71,7 @@
case 'D': chatty9p++; break;
case 'f': devfile = ARGF(); break;
case 'h': nbuckets = atoi(EARGF(usage())); break;
+ case 'w': npendingwrites = atoi(EARGF(usage())); break;
case 'r':
doream = 1;
/* fall through */
@@ -100,6 +103,9 @@
if (access(devfile, AREAD|AWRITE) == -1)
sysfatal("%s cannot access device", devfile);+
+ if(npendingwrites == 0)
+ npendingwrites = KiB;
formatinit();
--- a/sub.c
+++ b/sub.c
@@ -185,12 +185,6 @@
putbuf(sb);
}
-/* almost obsolete as all writes except for the free extents are synchronous */
-void
-sync(void)
-{-}
-
void
closefd(int fd)
{--- a/writer.c
+++ b/writer.c
@@ -1,10 +1,5 @@
#include "all.h"
-enum
-{- Npendingwrites = 32,
-};
-
/* Only 1 writer to maintain the sequence of writes.
Else, the directory entry could get written before the directory
content by another write process.
@@ -20,7 +15,8 @@
QLock lck; /* controls access to this queue */
Wbuf *head, *tail; /* linked list of dirty blocks yet to be written to the disk */
s32 n;
- Rendez isempty;
+ Rendez isfull; /* write throttling */
+ Rendez isempty; /* writer does not have to keep polling to find work */
} drts = {0};struct Wbuf
@@ -34,6 +30,7 @@
};
};
+u64 npendingwrites; /* write throttling */
u8 stopwrites = 0;
static void stats(void);
@@ -93,9 +90,10 @@
}
/* using canwlock() here as getbuf() could
have wlock()'ed the Iobuf too */
- if(drts.head != nil)
+ if(drts.head != nil){b = pluck(drts.head);
- else
+ rwakeup(&drts.isfull);
+ }else
b = nil;
if(chatty9p > 4 && b!=nil){ dprint("getwrite done b->blkno %llud\n", b->blkno);@@ -116,12 +114,8 @@
dprint("putwrite start p->blkno %llud\n", b->blkno);stats();
}
- if(drts.n > Npendingwrites){- if(drts.n < 0)
- panic("putwrite drts.n < 0\n");- if(chatty9p > 4)
- stats();
- }
+ if(drts.n > Npendingwrites)
+ rsleep(&drts.isfull);
w = emalloc9p(sizeof(Wbuf)+Rawblocksize);
w->blkno = b->blkno;
memcpy(&w->io, b->io, Rawblocksize);
@@ -188,6 +182,7 @@
// set the locks used by the Rendezes
drts.isempty.l = &drts.lck;
+ drts.isfull.l = &drts.lck;
switch(rfork(RFPROC|RFMEM)){case -1:
@@ -253,4 +248,11 @@
stats();
qunlock(&drts.lck);
return n;
-}
\ No newline at end of file
+}
+
+void
+sync(void)
+{+ while(drts.n > 0)
+ sleep(1000);
+}