At Mon, 25 Jun 2012 13:56:42 +0800,
Liu Yuan wrote:
>
> On 06/25/2012 01:42 PM, MORITA Kazutaka wrote:
> > At Sun, 24 Jun 2012 20:51:50 +0800,
> > Liu Yuan wrote:
> >>
> >> From: Liu Yuan <[email protected]>
> >>
> >> This is inspired by the observation that each Guest can issue as much
> >> as 4 requests in one go.
> >
> > Is it true for any kind of guest OSes?
> >
>
> Dunno others, but current Linux virtio_blk driver can only issue as much
> as 4 requests in one go. IDE driver is less than 4 I think. From the
> driver perspective, it seems that only scsi driver can issue more than 4
> requests in one go, but QEMU support to emulate scsi disk ?
>
> Anyway, this is just a hint. Suppose request size from guest is 512k,
> then 4M / 512k = 8, so at most 8 request can be issued to one sheep
> object. So I think 8 is enough.
Why do you assume the request size is 512k? Maybe I'm missing
something, and I'm fine with it if 8 is not too small.
> >
> >> @@ -42,9 +56,10 @@ static struct sockfd_cache sockfd_cache = {
> >>
> >> struct sockfd_cache_entry {
> >> struct rb_node rb;
> >> - int fd;
> >> - uint8_t refcount;
> >> struct node_id nid;
> >> +#define SOCKFD_CACHE_MAX_FD 8 /* How many FDs we cache for one node
> >> */
> >> + int fd[SOCKFD_CACHE_MAX_FD];
> >> + uint8_t fd_in_use[SOCKFD_CACHE_MAX_FD];
> >> };
> >
> > SOCKFD_CACHE_MAX_FD should be 12 because the default redundancy level
> > is 3?
> >
>
> why? I think FD number has nothing to do with redundancy, instead it is
> affected by how many requests Guest can issue in one go.
Ah, yes. I misunderstood your code, sorry.
Thanks,
Kazutaka
--
sheepdog mailing list
[email protected]
http://lists.wpkg.org/mailman/listinfo/sheepdog
