Re: [LTP] [PATCH v1] readahead02.c: Use fsync instead of sync

[Richard Palethorpe <rpalethorpe@suse.de>]

Hello,

Wei Gao via ltp <ltp@lists.linux.it> writes:

> Use fsync on test file instead of sync should faster than syncing
> whole system.

The test completes in less than a second in OpenQA. We don't want to
risk introducing a regression or spend time reviewing changes unless the
performance improvement solves a timeout.

I suggest you convert dup06 to the new API (for example) or investigate
a test failure.

>
> Signed-off-by: Wei Gao <wegao@suse.com>
> ---
>  .../kernel/syscalls/readahead/readahead02.c     | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/testcases/kernel/syscalls/readahead/readahead02.c b/testcases/kernel/syscalls/readahead/readahead02.c
> index 7acf4bb18..e04046bc3 100644
> --- a/testcases/kernel/syscalls/readahead/readahead02.c
> +++ b/testcases/kernel/syscalls/readahead/readahead02.c
> @@ -99,6 +99,17 @@ static void drop_caches(void)
>  	SAFE_FILE_PRINTF(DROP_CACHES_FNAME, "1");
>  }
>  
> +static void sync_drop_caches(void)
> +{
> +	int fd;
> +
> +	fd  = SAFE_OPEN(testfile, O_RDONLY);
> +	if (fsync(fd) == -1)
> +		tst_brk(TBROK | TERRNO, "fsync()");
> +	SAFE_CLOSE(fd);
> +	drop_caches();
> +}
> +
>  static unsigned long get_bytes_read(void)
>  {
>  	unsigned long ret;
> @@ -233,8 +244,7 @@ static void test_readahead(unsigned int n)
>  	read_testfile(tc, 0, testfile, testfile_size, &read_bytes, &usec,
>  		      &cached);
>  	cached_high = get_cached_size();
> -	sync();
> -	drop_caches();
> +	sync_drop_caches();
>  	cached_low = get_cached_size();
>  	cached_max = MAX(cached_max, cached_high - cached_low);
>  
> @@ -246,8 +256,7 @@ static void test_readahead(unsigned int n)
>  	else
>  		cached = 0;
>  
> -	sync();
> -	drop_caches();
> +	sync_drop_caches();
>  	cached_low = get_cached_size();
>  	tst_res(TINFO, "read_testfile(1)");
>  	ret = read_testfile(tc, 1, testfile, testfile_size, &read_bytes_ra,
> -- 
> 2.35.3


-- 
Thank you,
Richard.

-- 
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