Hi SeongJae:
On 12/8/21 8:49 PM, SeongJae Park wrote:
On Wed, 8 Dec 2021 14:29:40 +0800 Xin Hao <xhao@xxxxxxxxxxxxxxxxx> wrote:
Hi Xin,
Hi park:
On 12/1/21 11:04 PM, SeongJae Park wrote:
When wrong scheme action is requested via the debugfs interface, DAMON
prints an error message. Because the function returns error code, this
is not really needed. Because the code path is triggered by the user
specified input, this can result in kernel log mistakenly being messy.
Completely correct, but there will also be a problem that users can’t
quickly locate where the problem is,
Especially too many parameters need to be written into the interface.
I think it is necessary to add some debugging methods to help users find
the error without polluting the kernel log.
And i have an idea, like this:
in dbgfs, add a last_cmd_stat interface.
# echo "1 2 1 2 1 2 1 2 1 2 100 ..." > schemes
# cat last_cmd_stat
# wrong action 100
In this way, on the one hand, it will not pollute the kernel log, on the
other hand, it will help users find the cause of the operation
interface error.
Park, how do you think of about this idea, if ok, i will send a patch.
Thank you always for your great suggestions and efforts! BTW, I prefer to be
called with my first name ;)
Ha-Ha, Sorry!
I want DAMON kernel code to be as simple and small as possible, while putting
fancy but complicated features for user conveniences in user space tools like
DAMO[1]. In other words, I hope the DAMON debugfs interface to be used as an
interface for such user space tools, not an interface for human hands.
Ok, I know what you mean.
IMHO, implementing the feature you proposed in the kernel could make the code
slightly bigger, while it can easily implemented in user space. I therefore
think the feature would be better to be implemented in user space. If you
could send a pull request of the feature for DAMO, it would be so great.
Ok, i will do it, But there's a problem here, If the user does not use
the DAMO tools to operate the dbgfs interface,
the operation interface error will still hard to find the cause of errors.
[1] https://github.com/awslabs/damo
Thanks,
SJ
To avoid the case, this commit removes the message
Fixes: af122dd8f3c0 ("mm/damon/dbgfs: support DAMON-based Operation Schemes")
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
---
mm/damon/dbgfs.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
index 4bf4204444ab..5b628990ae6e 100644
--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -210,10 +210,8 @@ static struct damos **str_to_schemes(const char *str, ssize_t len,
&wmarks.low, &parsed);
if (ret != 18)
break;
- if (!damos_action_valid(action)) {
- pr_err("wrong action %d\n", action);
+ if (!damos_action_valid(action))
goto fail;
- }
if (min_sz > max_sz || min_nr_a > max_nr_a || min_age > max_age)
goto fail;
--
Best Regards!
Xin Hao
--
Best Regards!
Xin Hao
