Looking at this I believe that delayed allocation is enabled in the disk:
$ cat /sys/fs/ext4/sda5/delayed_allocation_blocks
2
Javi
On Wed, Feb 16, 2011 at 2:33 AM, Javi <javier.cabezas@xxxxxxxxx> wrote:
> 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:
>
> [ Â Â2.908858] EXT4-fs (sda5): mounted filesystem with ordered data
> mode. Opts: (null)
> [ Â 14.167465] EXT4-fs (sda5): re-mounted. Opts: errors=remount-ro,user_xattr
> [ Â 15.512701] EXT4-fs (sda5): re-mounted. Opts:
> errors=remount-ro,user_xattr,commit=0
> [ Â 20.801609] EXT4-fs (sda5): re-mounted. Opts:
> errors=remount-ro,user_xattr,commit=0
>
> How can I give you more information?
>
> Thanks,
> ÂJavi
>
> On Wed, Feb 16, 2011 at 2:12 AM, Yongqiang Yang <xiaoqiangnk@xxxxxxxxx> wrote:
>> WasÂext4 mounted with dealloc?
>>
>> On Mon, Feb 7, 2011 at 3:41 PM, Javi <javier.cabezas@xxxxxxxxx> wrote:
>>>
>>> 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:
>>>
>>> Â Â// Create the file
>>> Â Âsnprintf(tmp, FILENAME_MAX, "/tmp/testXXXXXX");
>>> Â Âint fd = mkstemp(tmp);
>>> Â Âif(fd < 0) return NULL;
>>> Â Âunlink(tmp);
>>>
>>> Â Âif(ftruncate(fd, count) < 0) {
>>> Â Â Â Âclose(fd);
>>> Â Â Â Âreturn NULL;
>>> Â Â}
>>> Â Â...
>>>
>>> Â Â// Create a mapping
>>> Â Âaddr = 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,
>>> ÂJavi
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
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>>
>>
>>
>> --
>> Best Wishes
>> Yongqiang Yang
>>
>>
>
>
>
> --
> Javi
>
--
Javi
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