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From e04ef476fd330485e5a88c7018d29c55cf411fe2 Mon Sep 17 00:00:00 2001
From: Richard W.M. Jones <rjones@redhat.com>
Date: Tue, 5 Oct 2010 09:54:10 +0100
Subject: [PATCH] Trace reads and writes to qemu block devices.
NB: This patch is not suitable for nor intended to go upstream in
its current form.
When qemu opens a block device, this patch creates a trace file
in /tmp with a name related to the block device. Reads and writes
to the device cause lines to be written to the trace file:
S <total_sectors>
W <sector> <nb_sectors>
R <sector> <nb_sectors>
'S' is the summary line, printed first which just tells you how
many sectors are on the device.
'W' and 'R' are writes and reads, for the range <sector> through
to <sector> + <nb_sectors> - 1.
---
block.c | 29 +++++++++++++++++++++++++++++
block_int.h | 3 +++
2 files changed, 32 insertions(+), 0 deletions(-)
diff --git a/block.c b/block.c
index ebbc376..26ead5b 100644
--- a/block.c
+++ b/block.c
@@ -474,6 +474,23 @@ static int bdrv_open_common(BlockDriverState *bs, const char *filename,
goto free_and_fail;
}
+ /* Open trace file in /tmp based on filename. XXX */
+ size_t len = strlen (filename);
+ char *trace_file = qemu_malloc (10 + len);
+ snprintf (trace_file, 10 + len, "/tmp/%s.qtr", filename);
+ size_t i;
+ for (i = 5; i < 5 + len; ++i) {
+ if (trace_file[i] == '/')
+ trace_file[i] = '_';
+ }
+ bs->trace_fp = fopen (trace_file, "w");
+ if (bs->trace_fp) {
+ setlinebuf (bs->trace_fp);
+ fprintf (bs->trace_fp, "S %" PRIi64 "\n", bs->total_sectors);
+ } else {
+ perror (trace_file);
+ }
+
#ifndef _WIN32
if (bs->is_temporary) {
unlink(filename);
@@ -665,6 +682,10 @@ void bdrv_close(BlockDriverState *bs)
bdrv_close(bs->file);
}
+ if (bs->trace_fp)
+ fclose (bs->trace_fp);
+ bs->trace_fp = NULL;
+
/* call the change callback */
bs->media_changed = 1;
if (bs->change_cb)
@@ -1995,6 +2016,10 @@ BlockDriverAIOCB *bdrv_aio_readv(BlockDriverState *bs, int64_t sector_num,
/* Update stats even though technically transfer has not happened. */
bs->rd_bytes += (unsigned) nb_sectors * BDRV_SECTOR_SIZE;
bs->rd_ops ++;
+
+ if (bs->trace_fp)
+ fprintf (bs->trace_fp,
+ "R %" PRIi64 " %d\n", sector_num, nb_sectors);
}
return ret;
@@ -2028,6 +2053,10 @@ BlockDriverAIOCB *bdrv_aio_writev(BlockDriverState *bs, int64_t sector_num,
if (bs->wr_highest_sector < sector_num + nb_sectors - 1) {
bs->wr_highest_sector = sector_num + nb_sectors - 1;
}
+
+ if (bs->trace_fp)
+ fprintf (bs->trace_fp,
+ "W %" PRIi64 " %d\n", sector_num, nb_sectors);
}
return ret;
diff --git a/block_int.h b/block_int.h
index e8e7156..03e7c9b 100644
--- a/block_int.h
+++ b/block_int.h
@@ -178,6 +178,9 @@ struct BlockDriverState {
uint64_t wr_ops;
uint64_t wr_highest_sector;
+ /* Trace to file. */
+ FILE *trace_fp;
+
/* Whether the disk can expand beyond total_sectors */
int growable;
--
1.7.3.1
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