f2fs: introduce f2fs_issue_flush to avoid redundant flush issue
Some storage devices show relatively high latencies to complete cache_flush
commands, even though their normal IO speed is prettry much high. In such
the case, it needs to merge cache_flush commands as much as possible to avoid
issuing them redundantly.
So, this patch introduces a mount option, "-o flush_merge", to mitigate such
the overhead.
If this option is enabled by user, F2FS merges the cache_flush commands and then
issues just one cache_flush on behalf of them. Once the single command is
finished, F2FS sends a completion signal to all the pending threads.
Note that, this option can be used under a workload consisting of very intensive
concurrent fsync calls, while the storage handles cache_flush commands slowly.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 9598340..d31b767 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -51,6 +51,7 @@
Opt_disable_ext_identify,
Opt_inline_xattr,
Opt_inline_data,
+ Opt_flush_merge,
Opt_err,
};
@@ -67,6 +68,7 @@
{Opt_disable_ext_identify, "disable_ext_identify"},
{Opt_inline_xattr, "inline_xattr"},
{Opt_inline_data, "inline_data"},
+ {Opt_flush_merge, "flush_merge"},
{Opt_err, NULL},
};
@@ -334,6 +336,9 @@
case Opt_inline_data:
set_opt(sbi, INLINE_DATA);
break;
+ case Opt_flush_merge:
+ set_opt(sbi, FLUSH_MERGE);
+ break;
default:
f2fs_msg(sb, KERN_ERR,
"Unrecognized mount option \"%s\" or missing value",
@@ -537,6 +542,8 @@
seq_puts(seq, ",disable_ext_identify");
if (test_opt(sbi, INLINE_DATA))
seq_puts(seq, ",inline_data");
+ if (test_opt(sbi, FLUSH_MERGE))
+ seq_puts(seq, ",flush_merge");
seq_printf(seq, ",active_logs=%u", sbi->active_logs);
return 0;