* [LTP] [PATCH COMMITTED] tst_device: do sync() before reading test block device stat file
@ 2020-01-02 1:52 Li Wang
2020-01-02 2:09 ` Yang Xu
2020-01-02 12:57 ` Cyril Hrubis
0 siblings, 2 replies; 13+ messages in thread
From: Li Wang @ 2020-01-02 1:52 UTC (permalink / raw)
To: ltp
To avoid FS deferred IO metadata/cache interferes test result, so we
do sync simply before the tst_dev_bytes_written invocation.
Signed-off-by: Li Wang <liwang@redhat.com>
Cc: Sumit Garg <sumit.garg@linaro.org>
Cc: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
---
testcases/kernel/syscalls/fdatasync/fdatasync03.c | 2 ++
testcases/kernel/syscalls/fsync/fsync04.c | 2 ++
testcases/kernel/syscalls/sync/sync03.c | 2 ++
testcases/kernel/syscalls/syncfs/syncfs01.c | 2 ++
4 files changed, 8 insertions(+)
diff --git a/testcases/kernel/syscalls/fdatasync/fdatasync03.c b/testcases/kernel/syscalls/fdatasync/fdatasync03.c
index ee50e75c9..032ac4b58 100644
--- a/testcases/kernel/syscalls/fdatasync/fdatasync03.c
+++ b/testcases/kernel/syscalls/fdatasync/fdatasync03.c
@@ -32,6 +32,8 @@ static void verify_fdatasync(void)
fd = SAFE_OPEN(FNAME, O_RDWR|O_CREAT, MODE);
+ sync();
+
tst_dev_bytes_written(tst_device->dev);
tst_fill_fd(fd, 0, TST_MB, FILE_SIZE_MB);
diff --git a/testcases/kernel/syscalls/fsync/fsync04.c b/testcases/kernel/syscalls/fsync/fsync04.c
index c67fc5692..3c1f45e94 100644
--- a/testcases/kernel/syscalls/fsync/fsync04.c
+++ b/testcases/kernel/syscalls/fsync/fsync04.c
@@ -32,6 +32,8 @@ static void verify_fsync(void)
fd = SAFE_OPEN(FNAME, O_RDWR|O_CREAT, MODE);
+ sync();
+
tst_dev_bytes_written(tst_device->dev);
tst_fill_fd(fd, 0, TST_MB, FILE_SIZE_MB);
diff --git a/testcases/kernel/syscalls/sync/sync03.c b/testcases/kernel/syscalls/sync/sync03.c
index a6f72d2ed..085ccfdeb 100644
--- a/testcases/kernel/syscalls/sync/sync03.c
+++ b/testcases/kernel/syscalls/sync/sync03.c
@@ -32,6 +32,8 @@ static void verify_sync(void)
fd = SAFE_OPEN(FNAME, O_RDWR|O_CREAT, MODE);
+ sync();
+
tst_dev_bytes_written(tst_device->dev);
tst_fill_fd(fd, 0, TST_MB, FILE_SIZE_MB);
diff --git a/testcases/kernel/syscalls/syncfs/syncfs01.c b/testcases/kernel/syscalls/syncfs/syncfs01.c
index 051a19ea6..3cf404450 100644
--- a/testcases/kernel/syscalls/syncfs/syncfs01.c
+++ b/testcases/kernel/syscalls/syncfs/syncfs01.c
@@ -33,6 +33,8 @@ static void verify_syncfs(void)
fd = SAFE_OPEN(FNAME, O_RDWR|O_CREAT, MODE);
+ sync();
+
tst_dev_bytes_written(tst_device->dev);
tst_fill_fd(fd, 0, TST_MB, FILE_SIZE_MB);
--
2.20.1
^ permalink raw reply related [flat|nested] 13+ messages in thread
* [LTP] [PATCH COMMITTED] tst_device: do sync() before reading test block device stat file
2020-01-02 1:52 [LTP] [PATCH COMMITTED] tst_device: do sync() before reading test block device stat file Li Wang
@ 2020-01-02 2:09 ` Yang Xu
2020-01-02 6:31 ` Li Wang
2020-01-02 12:57 ` Cyril Hrubis
1 sibling, 1 reply; 13+ messages in thread
From: Yang Xu @ 2020-01-02 2:09 UTC (permalink / raw)
To: ltp
Hi Li
> To avoid FS deferred IO metadata/cache interferes test result, so we
> do sync simply before the tst_dev_bytes_written invocation.
>
Looks good, acked. Also, I think we can mention it in
doc/test-writing-guidelines.txt when using this api.
Best Regards
Yang Xu
> Signed-off-by: Li Wang <liwang@redhat.com>
> Cc: Sumit Garg <sumit.garg@linaro.org>
> Cc: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
> ---
> testcases/kernel/syscalls/fdatasync/fdatasync03.c | 2 ++
> testcases/kernel/syscalls/fsync/fsync04.c | 2 ++
> testcases/kernel/syscalls/sync/sync03.c | 2 ++
> testcases/kernel/syscalls/syncfs/syncfs01.c | 2 ++
> 4 files changed, 8 insertions(+)
>
> diff --git a/testcases/kernel/syscalls/fdatasync/fdatasync03.c b/testcases/kernel/syscalls/fdatasync/fdatasync03.c
> index ee50e75c9..032ac4b58 100644
> --- a/testcases/kernel/syscalls/fdatasync/fdatasync03.c
> +++ b/testcases/kernel/syscalls/fdatasync/fdatasync03.c
> @@ -32,6 +32,8 @@ static void verify_fdatasync(void)
>
> fd = SAFE_OPEN(FNAME, O_RDWR|O_CREAT, MODE);
>
> + sync();
> +
> tst_dev_bytes_written(tst_device->dev);
>
> tst_fill_fd(fd, 0, TST_MB, FILE_SIZE_MB);
> diff --git a/testcases/kernel/syscalls/fsync/fsync04.c b/testcases/kernel/syscalls/fsync/fsync04.c
> index c67fc5692..3c1f45e94 100644
> --- a/testcases/kernel/syscalls/fsync/fsync04.c
> +++ b/testcases/kernel/syscalls/fsync/fsync04.c
> @@ -32,6 +32,8 @@ static void verify_fsync(void)
>
> fd = SAFE_OPEN(FNAME, O_RDWR|O_CREAT, MODE);
>
> + sync();
> +
> tst_dev_bytes_written(tst_device->dev);
>
> tst_fill_fd(fd, 0, TST_MB, FILE_SIZE_MB);
> diff --git a/testcases/kernel/syscalls/sync/sync03.c b/testcases/kernel/syscalls/sync/sync03.c
> index a6f72d2ed..085ccfdeb 100644
> --- a/testcases/kernel/syscalls/sync/sync03.c
> +++ b/testcases/kernel/syscalls/sync/sync03.c
> @@ -32,6 +32,8 @@ static void verify_sync(void)
>
> fd = SAFE_OPEN(FNAME, O_RDWR|O_CREAT, MODE);
>
> + sync();
> +
> tst_dev_bytes_written(tst_device->dev);
>
> tst_fill_fd(fd, 0, TST_MB, FILE_SIZE_MB);
> diff --git a/testcases/kernel/syscalls/syncfs/syncfs01.c b/testcases/kernel/syscalls/syncfs/syncfs01.c
> index 051a19ea6..3cf404450 100644
> --- a/testcases/kernel/syscalls/syncfs/syncfs01.c
> +++ b/testcases/kernel/syscalls/syncfs/syncfs01.c
> @@ -33,6 +33,8 @@ static void verify_syncfs(void)
>
> fd = SAFE_OPEN(FNAME, O_RDWR|O_CREAT, MODE);
>
> + sync();
> +
> tst_dev_bytes_written(tst_device->dev);
>
> tst_fill_fd(fd, 0, TST_MB, FILE_SIZE_MB);
>
^ permalink raw reply [flat|nested] 13+ messages in thread
* [LTP] [PATCH COMMITTED] tst_device: do sync() before reading test block device stat file
2020-01-02 2:09 ` Yang Xu
@ 2020-01-02 6:31 ` Li Wang
2020-01-02 6:46 ` Yang Xu
0 siblings, 1 reply; 13+ messages in thread
From: Li Wang @ 2020-01-02 6:31 UTC (permalink / raw)
To: ltp
On Thu, Jan 2, 2020 at 10:10 AM Yang Xu <xuyang2018.jy@cn.fujitsu.com>
wrote:
>
>
> Hi Li
> > To avoid FS deferred IO metadata/cache interferes test result, so we
> > do sync simply before the tst_dev_bytes_written invocation.
> >
> Looks good, acked. Also, I think we can mention it in
> doc/test-writing-guidelines.txt when using this api.
>
Ok, I will append one line as:
--- a/doc/test-writing-guidelines.txt
+++ b/doc/test-writing-guidelines.txt
@@ -1072,7 +1072,9 @@ unsigned long tst_dev_bytes_written(const char *dev);
-------------------------------------------------------------------------------
This function reads test block device stat file (/sys/block/<device>/stat)
and
-returns the bytes written since the last invocation of this function.
+returns the bytes written since the last invocation of this function. To
avoid
+FS deferred IO metadata/cache interferes the test result, we suggest doing
sync()
+before the tst_dev_bytes_written first invocation.
--
Regards,
Li Wang
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* [LTP] [PATCH COMMITTED] tst_device: do sync() before reading test block device stat file
2020-01-02 6:31 ` Li Wang
@ 2020-01-02 6:46 ` Yang Xu
2020-01-03 7:25 ` Li Wang
0 siblings, 1 reply; 13+ messages in thread
From: Yang Xu @ 2020-01-02 6:46 UTC (permalink / raw)
To: ltp
on 2020/01/02 14:31, Li Wang wrote:
>
>
> On Thu, Jan 2, 2020 at 10:10 AM Yang Xu <xuyang2018.jy@cn.fujitsu.com
> <mailto:xuyang2018.jy@cn.fujitsu.com>> wrote:
>
>
>
> Hi Li
> > To avoid FS deferred IO metadata/cache interferes test result, so we
> > do sync simply before the tst_dev_bytes_written invocation.
> >
> Looks good, acked. Also, I think we can mention it in
> doc/test-writing-guidelines.txt when using this api.
>
>
> Ok, I will append one line as:
> --- a/doc/test-writing-guidelines.txt
> +++ b/doc/test-writing-guidelines.txt
> @@ -1072,7 +1072,9 @@ unsigned long tst_dev_bytes_written(const char *dev);
> ?-------------------------------------------------------------------------------
>
> ?This function reads test block device stat file
> (/sys/block/<device>/stat) and
> -returns the bytes written since the last invocation of this function.
> +returns the bytes written since the last invocation of this function.
> To avoid
> +FS deferred IO metadata/cache interferes the test result, we suggest
> doing sync()
> +before the tst_dev_bytes_written first invocation.
OK.
I also meet another problem when using this api on old kernel.
tst_device.c:395: CONF: Test device stat file: /sys/block/loop0/stat broken
/sys/block/loop0/stat is all 0 and case reports TCONF. on new kernel,
this value is normal. This is a block layer or loop device driver
modifition several yeas ago?
ps:I know ltp used LOOP_SET_FD to make loop device simulate other
filesystems. I am trying to find a generic way about this api.
Best Regards
Yang Xu
>
> --
> Regards,
> Li Wang
^ permalink raw reply [flat|nested] 13+ messages in thread
* [LTP] [PATCH COMMITTED] tst_device: do sync() before reading test block device stat file
2020-01-02 6:46 ` Yang Xu
@ 2020-01-03 7:25 ` Li Wang
2020-01-03 7:41 ` Yang Xu
0 siblings, 1 reply; 13+ messages in thread
From: Li Wang @ 2020-01-03 7:25 UTC (permalink / raw)
To: ltp
On Thu, Jan 2, 2020 at 2:46 PM Yang Xu <xuyang2018.jy@cn.fujitsu.com> wrote:
>
>
> on 2020/01/02 14:31, Li Wang wrote:
> >
> >
> > On Thu, Jan 2, 2020 at 10:10 AM Yang Xu <xuyang2018.jy@cn.fujitsu.com
> > <mailto:xuyang2018.jy@cn.fujitsu.com>> wrote:
> >
> >
> >
> > Hi Li
> > > To avoid FS deferred IO metadata/cache interferes test result, so
> we
> > > do sync simply before the tst_dev_bytes_written invocation.
> > >
> > Looks good, acked. Also, I think we can mention it in
> > doc/test-writing-guidelines.txt when using this api.
> >
> >
> > Ok, I will append one line as:
> > --- a/doc/test-writing-guidelines.txt
> > +++ b/doc/test-writing-guidelines.txt
> > @@ -1072,7 +1072,9 @@ unsigned long tst_dev_bytes_written(const char
> *dev);
> >
> -------------------------------------------------------------------------------
> >
> > This function reads test block device stat file
> > (/sys/block/<device>/stat) and
> > -returns the bytes written since the last invocation of this function.
> > +returns the bytes written since the last invocation of this function.
> > To avoid
> > +FS deferred IO metadata/cache interferes the test result, we suggest
> > doing sync()
> > +before the tst_dev_bytes_written first invocation.
> OK.
>
> I also meet another problem when using this api on old kernel.
>
> tst_device.c:395: CONF: Test device stat file: /sys/block/loop0/stat broken
>
> /sys/block/loop0/stat is all 0 and case reports TCONF. on new kernel,
> this value is normal. This is a block layer or loop device driver
> modifition several yeas ago?
>
It sounds like a kernel issue, can you tell which kernel version you did
test?
>
> ps:I know ltp used LOOP_SET_FD to make loop device simulate other
> filesystems. I am trying to find a generic way about this api.
>
> Best Regards
> Yang Xu
> >
> > --
> > Regards,
> > Li Wang
>
>
>
--
Regards,
Li Wang
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* [LTP] [PATCH COMMITTED] tst_device: do sync() before reading test block device stat file
2020-01-03 7:25 ` Li Wang
@ 2020-01-03 7:41 ` Yang Xu
2020-01-03 10:03 ` Yang Xu
0 siblings, 1 reply; 13+ messages in thread
From: Yang Xu @ 2020-01-03 7:41 UTC (permalink / raw)
To: ltp
on 2020/01/03 15:25, Li Wang wrote:
>
>
> On Thu, Jan 2, 2020 at 2:46 PM Yang Xu <xuyang2018.jy@cn.fujitsu.com
> <mailto:xuyang2018.jy@cn.fujitsu.com>> wrote:
>
>
>
> on 2020/01/02 14:31, Li Wang wrote:
> >
> >
> > On Thu, Jan 2, 2020 at 10:10 AM Yang Xu
> <xuyang2018.jy@cn.fujitsu.com <mailto:xuyang2018.jy@cn.fujitsu.com>
> > <mailto:xuyang2018.jy@cn.fujitsu.com
> <mailto:xuyang2018.jy@cn.fujitsu.com>>> wrote:
> >
> >
> >
> >? ? ?Hi Li
> >? ? ? > To avoid FS deferred IO metadata/cache interferes test
> result, so we
> >? ? ? > do sync simply before the tst_dev_bytes_written invocation.
> >? ? ? >
> >? ? ?Looks good, acked. Also, I think we can mention it in
> >? ? ?doc/test-writing-guidelines.txt when using this api.
> >
> >
> > Ok, I will append one line as:
> > --- a/doc/test-writing-guidelines.txt
> > +++ b/doc/test-writing-guidelines.txt
> > @@ -1072,7 +1072,9 @@ unsigned long tst_dev_bytes_written(const
> char *dev);
> >
> ?-------------------------------------------------------------------------------
> >
> >? ?This function reads test block device stat file
> > (/sys/block/<device>/stat) and
> > -returns the bytes written since the last invocation of this
> function.
> > +returns the bytes written since the last invocation of this
> function.
> > To avoid
> > +FS deferred IO metadata/cache interferes the test result, we
> suggest
> > doing sync()
> > +before the tst_dev_bytes_written first invocation.
> OK.
>
> I also meet another problem when using this api on old kernel.
>
> tst_device.c:395: CONF: Test device stat file: /sys/block/loop0/stat
> broken
>
> /sys/block/loop0/stat is all 0 and case reports TCONF. on new kernel,
> this value is normal. This is a block layer or loop device driver
> modifition several yeas ago?
>
>
> It sounds like a kernel issue, can you tell which kernel version you did
> test?
>
I test this on 3.10.0-1101.el7.x86_64. It also reports TCONF on old
fedora such as fedora 20,21. I guess loop driver modification(I am
verifying ...) causes it.
>
> ps:I know ltp used LOOP_SET_FD to make loop device simulate other
> filesystems. I am trying to find a generic way about this api.
>
> Best Regards
> Yang Xu
> >
> > --
> > Regards,
> > Li Wang
>
>
>
>
> --
> Regards,
> Li Wang
^ permalink raw reply [flat|nested] 13+ messages in thread
* [LTP] [PATCH COMMITTED] tst_device: do sync() before reading test block device stat file
2020-01-03 7:41 ` Yang Xu
@ 2020-01-03 10:03 ` Yang Xu
0 siblings, 0 replies; 13+ messages in thread
From: Yang Xu @ 2020-01-03 10:03 UTC (permalink / raw)
To: ltp
Hi Li
>
>
> on 2020/01/03 15:25, Li Wang wrote:
>>
>>
>> On Thu, Jan 2, 2020 at 2:46 PM Yang Xu <xuyang2018.jy@cn.fujitsu.com
>> <mailto:xuyang2018.jy@cn.fujitsu.com>> wrote:
>>
>>
>>
>> ??? on 2020/01/02 14:31, Li Wang wrote:
>> ???? >
>> ???? >
>> ???? > On Thu, Jan 2, 2020 at 10:10 AM Yang Xu
>> ??? <xuyang2018.jy@cn.fujitsu.com <mailto:xuyang2018.jy@cn.fujitsu.com>
>> ???? > <mailto:xuyang2018.jy@cn.fujitsu.com
>> ??? <mailto:xuyang2018.jy@cn.fujitsu.com>>> wrote:
>> ???? >
>> ???? >
>> ???? >
>> ???? >? ? ?Hi Li
>> ???? >? ? ? > To avoid FS deferred IO metadata/cache interferes test
>> ??? result, so we
>> ???? >? ? ? > do sync simply before the tst_dev_bytes_written invocation.
>> ???? >? ? ? >
>> ???? >? ? ?Looks good, acked. Also, I think we can mention it in
>> ???? >? ? ?doc/test-writing-guidelines.txt when using this api.
>> ???? >
>> ???? >
>> ???? > Ok, I will append one line as:
>> ???? > --- a/doc/test-writing-guidelines.txt
>> ???? > +++ b/doc/test-writing-guidelines.txt
>> ???? > @@ -1072,7 +1072,9 @@ unsigned long tst_dev_bytes_written(const
>> ??? char *dev);
>> ???? >
>> ?-------------------------------------------------------------------------------
>>
>> ???? >
>> ???? >? ?This function reads test block device stat file
>> ???? > (/sys/block/<device>/stat) and
>> ???? > -returns the bytes written since the last invocation of this
>> ??? function.
>> ???? > +returns the bytes written since the last invocation of this
>> ??? function.
>> ???? > To avoid
>> ???? > +FS deferred IO metadata/cache interferes the test result, we
>> ??? suggest
>> ???? > doing sync()
>> ???? > +before the tst_dev_bytes_written first invocation.
>> ??? OK.
>>
>> ??? I also meet another problem when using this api on old kernel.
>>
>> ??? tst_device.c:395: CONF: Test device stat file: /sys/block/loop0/stat
>> ??? broken
>>
>> ??? /sys/block/loop0/stat is all 0 and case reports TCONF. on new kernel,
>> ??? this value is normal. This is a block layer or loop device driver
>> ??? modifition several yeas ago?
>>
>>
>> It sounds like a kernel issue, can you tell which kernel version you
>> did test?
>>
> I test this on 3.10.0-1101.el7.x86_64. It also reports TCONF on old
> fedora such as fedora 20,21. I guess loop driver modification(I am
> verifying ...) causes it.
Before kernel commit b5dd2f6047ca[1] (block: loop: improve performance
via blk-mq), this /sys/block/loop0/stat value is all 0 for loop device
because loop device uses its own make requestion function but not blk
end request (so these value can not be counted). After onversion of loop
to blk-mq, this value is normal. This patch was merged into upstream
kernel since v4.0. When using tst_dev_bytes_written api(using loop
device as block device) on older kernel, this /sys/block/loop0/stat
value is all 0 and we should mention user to export $LTP_DEV to test.
Also, we can do it in other patch.
[1]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/block/loop.c?id=b5dd2f6047ca108001328aac0e8588edd15f1778
ps:I don't know block device(bio,request) or loop driver very much. If I
was wrong, please feel free to correct me.
Best Regards
Yang Xu
>>
>> ??? ps:I know ltp used LOOP_SET_FD to make loop device simulate other
>> ??? filesystems. I am trying to find a generic way about this api.
>>
>> ??? Best Regards
>> ??? Yang Xu
>> ???? >
>> ???? > --
>> ???? > Regards,
>> ???? > Li Wang
>>
>>
>>
>>
>> --
>> Regards,
>> Li Wang
>
>
>
^ permalink raw reply [flat|nested] 13+ messages in thread
* [LTP] [PATCH COMMITTED] tst_device: do sync() before reading test block device stat file
2020-01-02 1:52 [LTP] [PATCH COMMITTED] tst_device: do sync() before reading test block device stat file Li Wang
2020-01-02 2:09 ` Yang Xu
@ 2020-01-02 12:57 ` Cyril Hrubis
2020-01-03 7:24 ` Li Wang
1 sibling, 1 reply; 13+ messages in thread
From: Cyril Hrubis @ 2020-01-02 12:57 UTC (permalink / raw)
To: ltp
Hi!
> To avoid FS deferred IO metadata/cache interferes test result, so we
> do sync simply before the tst_dev_bytes_written invocation.
Can we do fsync() on the fd instead of full sync()? That should be
slightly faster.
--
Cyril Hrubis
chrubis@suse.cz
^ permalink raw reply [flat|nested] 13+ messages in thread
* [LTP] [PATCH COMMITTED] tst_device: do sync() before reading test block device stat file
2020-01-02 12:57 ` Cyril Hrubis
@ 2020-01-03 7:24 ` Li Wang
2020-01-06 10:05 ` Cyril Hrubis
0 siblings, 1 reply; 13+ messages in thread
From: Li Wang @ 2020-01-03 7:24 UTC (permalink / raw)
To: ltp
Hi Cyril,
On Thu, Jan 2, 2020 at 8:58 PM Cyril Hrubis <chrubis@suse.cz> wrote:
> Hi!
> > To avoid FS deferred IO metadata/cache interferes test result, so we
> > do sync simply before the tst_dev_bytes_written invocation.
>
> Can we do fsync() on the fd instead of full sync()? That should be
> slightly faster.
>
Probably you miss the previous discussed [1], we use sync() here because we
do want to make sure all FS metadata/cache being written back before the
testing since there is no obtainable file descriptor 'fd' for the ext4
deferred IO (e.g. initialize the journal and inode tables).
If I was wrong here, feel free to correct me.
[1] http://lists.linux.it/pipermail/ltp/2019-December/014792.html
--
Regards,
Li Wang
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* [LTP] [PATCH COMMITTED] tst_device: do sync() before reading test block device stat file
2020-01-03 7:24 ` Li Wang
@ 2020-01-06 10:05 ` Cyril Hrubis
2020-01-06 10:35 ` Cyril Hrubis
2020-01-07 6:13 ` Li Wang
0 siblings, 2 replies; 13+ messages in thread
From: Cyril Hrubis @ 2020-01-06 10:05 UTC (permalink / raw)
To: ltp
Hi!
> > > To avoid FS deferred IO metadata/cache interferes test result, so we
> > > do sync simply before the tst_dev_bytes_written invocation.
> >
> > Can we do fsync() on the fd instead of full sync()? That should be
> > slightly faster.
> >
>
> Probably you miss the previous discussed [1], we use sync() here because we
> do want to make sure all FS metadata/cache being written back before the
> testing since there is no obtainable file descriptor 'fd' for the ext4
> deferred IO (e.g. initialize the journal and inode tables).
Ah, right, we measure I/O to the whole device, so we would have to sync
the device in question. Then syncfs() on the fd we got should work
right? And it should avoid syncing unrelated filesystems as well.
--
Cyril Hrubis
chrubis@suse.cz
^ permalink raw reply [flat|nested] 13+ messages in thread
* [LTP] [PATCH COMMITTED] tst_device: do sync() before reading test block device stat file
2020-01-06 10:05 ` Cyril Hrubis
@ 2020-01-06 10:35 ` Cyril Hrubis
2020-01-07 6:16 ` Li Wang
2020-01-07 6:13 ` Li Wang
1 sibling, 1 reply; 13+ messages in thread
From: Cyril Hrubis @ 2020-01-06 10:35 UTC (permalink / raw)
To: ltp
Hi!
> > > > To avoid FS deferred IO metadata/cache interferes test result, so we
> > > > do sync simply before the tst_dev_bytes_written invocation.
> > >
> > > Can we do fsync() on the fd instead of full sync()? That should be
> > > slightly faster.
> > >
> >
> > Probably you miss the previous discussed [1], we use sync() here because we
> > do want to make sure all FS metadata/cache being written back before the
> > testing since there is no obtainable file descriptor 'fd' for the ext4
> > deferred IO (e.g. initialize the journal and inode tables).
>
> Ah, right, we measure I/O to the whole device, so we would have to sync
> the device in question. Then syncfs() on the fd we got should work
> right? And it should avoid syncing unrelated filesystems as well.
It wouldn't probably harm to create an inline function in the test
library just for a sake of documentation, something as:
static inline void tst_dev_sync(int fd)
{
syncfs(fd);
}
Then we end up calling:
tst_dev_sync(fd);
tst_dev_bytes_written(device);
--
Cyril Hrubis
chrubis@suse.cz
^ permalink raw reply [flat|nested] 13+ messages in thread* [LTP] [PATCH COMMITTED] tst_device: do sync() before reading test block device stat file
2020-01-06 10:35 ` Cyril Hrubis
@ 2020-01-07 6:16 ` Li Wang
0 siblings, 0 replies; 13+ messages in thread
From: Li Wang @ 2020-01-07 6:16 UTC (permalink / raw)
To: ltp
On Mon, Jan 6, 2020 at 6:35 PM Cyril Hrubis <chrubis@suse.cz> wrote:
> Hi!
> > > > > To avoid FS deferred IO metadata/cache interferes test result, so
> we
> > > > > do sync simply before the tst_dev_bytes_written invocation.
> > > >
> > > > Can we do fsync() on the fd instead of full sync()? That should be
> > > > slightly faster.
> > > >
> > >
> > > Probably you miss the previous discussed [1], we use sync() here
> because we
> > > do want to make sure all FS metadata/cache being written back before
> the
> > > testing since there is no obtainable file descriptor 'fd' for the ext4
> > > deferred IO (e.g. initialize the journal and inode tables).
> >
> > Ah, right, we measure I/O to the whole device, so we would have to sync
> > the device in question. Then syncfs() on the fd we got should work
> > right? And it should avoid syncing unrelated filesystems as well.
>
> It wouldn't probably harm to create an inline function in the test
> library just for a sake of documentation, something as:
>
> static inline void tst_dev_sync(int fd)
> {
> syncfs(fd);
> }
>
>
> Then we end up calling:
>
> tst_dev_sync(fd);
> tst_dev_bytes_written(device);
>
Agree.
--
Regards,
Li Wang
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* [LTP] [PATCH COMMITTED] tst_device: do sync() before reading test block device stat file
2020-01-06 10:05 ` Cyril Hrubis
2020-01-06 10:35 ` Cyril Hrubis
@ 2020-01-07 6:13 ` Li Wang
1 sibling, 0 replies; 13+ messages in thread
From: Li Wang @ 2020-01-07 6:13 UTC (permalink / raw)
To: ltp
Hi Cyril,
On Mon, Jan 6, 2020 at 6:06 PM Cyril Hrubis <chrubis@suse.cz> wrote:
> Hi!
> > > > To avoid FS deferred IO metadata/cache interferes test result, so we
> > > > do sync simply before the tst_dev_bytes_written invocation.
> > >
> > > Can we do fsync() on the fd instead of full sync()? That should be
> > > slightly faster.
> > >
> >
> > Probably you miss the previous discussed [1], we use sync() here because
> we
> > do want to make sure all FS metadata/cache being written back before the
> > testing since there is no obtainable file descriptor 'fd' for the ext4
> > deferred IO (e.g. initialize the journal and inode tables).
>
> Ah, right, we measure I/O to the whole device, so we would have to sync
> the device in question. Then syncfs() on the fd we got should work
> right? And it should avoid syncing unrelated filesystems as well.
>
Good point, I double read the fsync() and syncfs() manual page. It looks
like syncfs() is not the same as the previous function, it synchronizes the
file system containing file referred to by the open file descriptor fd, I
mixed them before, to be honest.
--
Regards,
Li Wang
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end of thread, other threads:[~2020-01-07 6:16 UTC | newest]
Thread overview: 13+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2020-01-02 1:52 [LTP] [PATCH COMMITTED] tst_device: do sync() before reading test block device stat file Li Wang
2020-01-02 2:09 ` Yang Xu
2020-01-02 6:31 ` Li Wang
2020-01-02 6:46 ` Yang Xu
2020-01-03 7:25 ` Li Wang
2020-01-03 7:41 ` Yang Xu
2020-01-03 10:03 ` Yang Xu
2020-01-02 12:57 ` Cyril Hrubis
2020-01-03 7:24 ` Li Wang
2020-01-06 10:05 ` Cyril Hrubis
2020-01-06 10:35 ` Cyril Hrubis
2020-01-07 6:16 ` Li Wang
2020-01-07 6:13 ` Li Wang
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