[PATCH 1/2] Added replay_rebase option to run multi-threaded log replay on different disk sectors.

[Taisuke Yamada <tai@rakugaki.org>]

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Hi.

I'm now trying to run multi-threaded log replay, and noticed
all threads are accessing same sector on a disk. Of course,
this is an expected behavior of "replay".

But since I also wanted to have each thread accessing different
parts of the disk to increase a load, but still following the
access pattern of the original, I added "replay_rebase" option to
shift offset of IO request for each thread.

Althrough there's "1/2" in the subject, this patch is complete
by itself. Next one (2/2) is related, but handles different issue.

Signed-off-by: Taisuke Yamada <tai@rakugaki.org>
---
 fio.h     |    1 +
 log.c     |    2 +-
 options.c |    8 ++++++++
 3 files changed, 10 insertions(+), 1 deletions(-)



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diff --git a/fio.h b/fio.h
index 6eb270d..b28e0ae 100644
--- a/fio.h
+++ b/fio.h
@@ -358,6 +358,7 @@ struct thread_options {
 	unsigned int gtod_offload;
 	enum fio_cs clocksource;
 	unsigned int no_stall;
+	unsigned int replay_rebase;
 	unsigned int trim_percentage;
 	unsigned int trim_batch;
 	unsigned int trim_zero;
diff --git a/log.c b/log.c
index f962864..57fc0f4 100644
--- a/log.c
+++ b/log.c
@@ -129,7 +129,7 @@ int read_iolog_get(struct thread_data *td, struct io_u *io_u)
 
 		io_u->ddir = ipo->ddir;
 		if (ipo->ddir != DDIR_WAIT) {
-			io_u->offset = ipo->offset;
+			io_u->offset = ipo->offset + td->o.replay_rebase * td->thread_number;
 			io_u->buflen = ipo->len;
 			io_u->file = td->files[ipo->fileno];
 			get_file(io_u->file);
diff --git a/options.c b/options.c
index 74c24d0..aba14b1 100644
--- a/options.c
+++ b/options.c
@@ -1654,6 +1654,14 @@ static struct fio_option options[FIO_MAX_OPTS] = {
 		.help	= "Replay all I/O onto this device, regardless of trace device",
 	},
 	{
+		.name	= "replay_rebase",
+		.type	= FIO_OPT_INT,
+		.off1	= td_var_offset(replay_rebase),
+		.def	= "0",
+		.parent	= "read_iolog",
+		.help	= "Apply given offset for IO replay. Mainly for parallel replay.",
+	},
+	{
 		.name	= "exec_prerun",
 		.type	= FIO_OPT_STR_STORE,
 		.off1	= td_var_offset(exec_prerun),