Re: [fuse-devel] big_writes option does not work

[Miklos S. <mi...@sz...>]

On Mon, Oct 14, 2013 at 4:16 PM, Lukáš Kvídera <kvi...@st...> wrote:
> This command is ok.
>
> write[140290006456912] 131072 bytes to 0 flags: 0x8001
>    write[140290006456912] 131072 bytes to 0
>    unique: 31, success, outsize: 24
> unique: 32, opcode: WRITE (16), nodeid: 2, insize: 131152
> write[140290006456912] 131072 bytes to 131072 flags: 0x8001
>    write[140290006456912] 131072 bytes to 131072
>    unique: 32, success, outsize: 24
>
>
> So the problem is in applications above?

Sort of.  Normally the kernel buffers writes, and so the size of the
write doesn't make much difference, which is why application sometimes
choose a smaller than optimal size.

Another possible reason is that some applications honor st_blksize,
which is supposed to be the optimal I/O size.  You can try tuning this
in your fuse filesystem.

Maxim Patlasov is currently working on a patchset to enable write
buffering for fuse, which will make this issue go away.

Thanks,
Miklos