Re: [Qemu-devel] [PATCH 4/5] hw/9pfs: use g_strdup_printf() instead of PATH_MAX limitation

[Chen Gang]

On 03/08/2014 09:58 PM, Chen Gang wrote:
> OK, thanks.
>
> Next, I will/should continue to analyse the performance issue for 9pfs
> when users drop into a long directory path under bash shell.
>

After have a test, I am sure it is not 9pfs issue, either not Qemu's
issue, it's Linux kernel vfs or block sub-systems' issue. The related
test environments (originally, our 9pfs is upper on ext4):

 - for ext4 file system under my Fedora laptop (Qemu does not start).

 - for ntfs file system under my Fedora laptop (Qemu does not start).

 - for ext4 file system under my Ubuntu in Qemu.

For a very long file name (e.g. > 3K long), all of them are very very
slow. (and I also tested the ext2 /boot partition under Ubuntu in Qemu,
it is not slow, I guess the reson is its partition size is small).


Next, I will/shall communicate with upstream kernel for it.  :-)


> Although I am not quite sure, hope I can find the root cause within
> month (2014-03-31).
>
> Welcome any suggestions, discussions, and completions for it.
>
> Thanks.
>


-- 
Chen Gang

Open, share and attitude like air, water and life which God blessed