I suppose they are caused by the Ubuntu initialization scripts. If you
look at the timestamp, you can see that they are early in the boot
process.

Javi

On Wed, Feb 16, 2011 at 2:55 AM, Yongqiang Yang [off-list ref] wrote:

On Wed, Feb 16, 2011 at 4:33 PM, Javi [off-list ref] wrote:

quoted

I am using the current mount options:

UUID=46fc675c-f196-4be2-bf4d-461d473de6b1 / ext4
errors=remount-ro,user_xattr 0 1

And the dmesg messages I get are:

[    2.908858] EXT4-fs (sda5): mounted filesystem with ordered data
mode. Opts: (null)
[   14.167465] EXT4-fs (sda5): re-mounted. Opts:
errors=remount-ro,user_xattr
[   15.512701] EXT4-fs (sda5): re-mounted. Opts:
errors=remount-ro,user_xattr,commit=0
[   20.801609] EXT4-fs (sda5): re-mounted. Opts:
errors=remount-ro,user_xattr,commit=0

How can I give you more information?

With dealloc enabled, temporary files with short life do not cause I/Os.
It seems that somebody
triggers something like a 'sync'.

Why are there several remounts here, manual or not?

quoted

Thanks,
 Javi

On Wed, Feb 16, 2011 at 2:12 AM, Yongqiang Yang [off-list ref]
wrote:

quoted

Was ext4 mounted with dealloc?

On Mon, Feb 7, 2011 at 3:41 PM, Javi [off-list ref] wrote:

quoted

I am developing a software based DSM. In order to avoid concurrent
updates on a memory page that is being updated by the runtime I am
using a shadow mapping to perform the updates. This mappings are
created by opening a file, unlinking it and mmap-ing on the file
descriptor. Everything is working but I am experiencing heavy disk I/O
during execution on a machine with a single ext4 file system. Other
machines that use ext3 partitions don't exhibit this behavior (there
is no disk I/O at all). This machine is using the kernel version
2.6.35-25-generic.

The exact steps performed to create the mappings are:

   // Create the file
   snprintf(tmp, FILENAME_MAX, "/tmp/testXXXXXX");
   int fd = mkstemp(tmp);
   if(fd < 0) return NULL;
   unlink(tmp);

   if(ftruncate(fd, count) < 0) {
       close(fd);
       return NULL;
   }
   ...

   // Create a mapping
   addr = mmap(NULL, count, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);


Does ext4 write to mmap'ed files although they don't have a name in
the file system? Am I doing anything wrong?

Thanks,
 Javi
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--
Best Wishes
Yongqiang Yang

--
Javi

--
Best Wishes
Yongqiang Yang

-- 
Javi
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