> On Dec 3, 2021, at 8:24 PM, Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
>
> On Sat, Dec 04, 2021 at 12:35:11AM +0000, Chuck Lever III wrote:
>>
>>> On Dec 3, 2021, at 5:39 PM, Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
>>>
>>> On Fri, Dec 03, 2021 at 10:07:19PM +0000, Chuck Lever III wrote:
>>>>
>>>>
>>>>>> On Dec 3, 2021, at 4:55 PM, Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
>>>>>
>>>>> From: "J. Bruce Fields" <bfields@xxxxxxxxxx>
>>>>>
>>>>> Currently nfsdcld is doing three fdatasyncs for each upcall. Based on
>>>>> SQLite documentation, WAL mode should also be safe, and I can confirm
>>>>> from an strace that it results in only one fdatasync each.
>>>>>
>>>>> This may be a bottleneck e.g. when lots of clients are being created or
>>>>> expired at once (e.g. on reboot).
>>>>>
>>>>> Not bothering with error checking, as this is just an optimization and
>>>>> nfsdcld will still function without. (Might be better to log something
>>>>> on failure, though.)
>>>>
>>>> I'm in full philosophical agreement for performance improvements
>>>> in this area. There are some caveats for WAL:
>>>>
>>>> - It requires SQLite v3.7.0 (2010). configure.ac may need to be
>>>> updated.
>>>
>>> Makes sense. But I dug around a bit, and how to do this is a total
>>> mystery to me....
>>
>> aclocal/libsqlite3.m4 has an SQLITE_VERSION_NUMBER check.
>
> I looked got stuck trying to figure out why the #%^ it's comparing to
> SQLITE_VERSION_NUMBER. OK, I see now, it's just some sanity check.
> Here's take 2.
>
> --b.
>
> From c22d3a2d8576273934773fefac933d4f8e04776b Mon Sep 17 00:00:00 2001
> From: "J. Bruce Fields" <bfields@xxxxxxxxxx>
> Date: Fri, 3 Dec 2021 10:27:53 -0500
> Subject: [PATCH] nfsdcld: use WAL journal for faster commits
>
> Currently nfsdcld is doing three fdatasyncs for each upcall. Based on
> SQLite documentation, WAL mode should also be safe, and I can confirm
> from an strace that it results in only one fdatasync each.
>
> This may be a bottleneck e.g. when lots of clients are being created or
> expired at once (e.g. on reboot).
>
> Not bothering with error checking, as this is just an optimization and
> nfsdcld will still function without. (Might be better to log something
> on failure, though.)
>
> Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
Nice.
Reviewed-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
> ---
> aclocal/libsqlite3.m4 | 2 +-
> utils/nfsdcld/sqlite.c | 2 ++
> 2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/aclocal/libsqlite3.m4 b/aclocal/libsqlite3.m4
> index 8c38993cbba8..c3beb4d56f0c 100644
> --- a/aclocal/libsqlite3.m4
> +++ b/aclocal/libsqlite3.m4
> @@ -22,7 +22,7 @@ AC_DEFUN([AC_SQLITE3_VERS], [
> int vers = sqlite3_libversion_number();
>
> return vers != SQLITE_VERSION_NUMBER ||
> - vers < 3003000;
> + vers < 3007000;
> }
> ], [libsqlite3_cv_is_recent=yes], [libsqlite3_cv_is_recent=no],
> [libsqlite3_cv_is_recent=unknown])
> diff --git a/utils/nfsdcld/sqlite.c b/utils/nfsdcld/sqlite.c
> index 03016fb95823..eabb0daa95f5 100644
> --- a/utils/nfsdcld/sqlite.c
> +++ b/utils/nfsdcld/sqlite.c
> @@ -826,6 +826,8 @@ sqlite_prepare_dbh(const char *topdir)
> goto out_close;
> }
>
> + sqlite3_exec(dbh, "PRAGMA journal_mode = WAL;", NULL, NULL, NULL);
> +
> ret = sqlite_query_schema_version();
> switch (ret) {
> case CLD_SQLITE_LATEST_SCHEMA_VERSION:
> --
> 2.33.1
--
Chuck Lever
