Re: [Xen-devel] [tapdisk2][PATCH1/1] Fix vreq with error of -EBUSY fails 100 times too soon

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2014-02-28 at 22:50 +0800, gordongong0350@xxxxxxxxx wrote:
> Fix vreq with error of -EBUSY fails 100 times too soon,  that return

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Ian.

>  EIO to td device layer. If this td
> device request is metadata of filesystem, the result is not good at
> all.
> 
> 
> To reproduce it witch  "./iozone -I -s 2G -r 512k -r 1m -r 2m -r 4m -i
> 0 -i 1 -f /data/iozone_test.tmp",
> the result is input/output error & iozone is stopped.
> 
> 
> 
> 
> 
> 
> 
> 
> From ccc0ce3aede1f5c920036847ddb16b25969be7ba Mon Sep 17 00:00:00 2001
> From: Xiaodong Gong <gordongong0350@xxxxxxxxx>
> Date: Fri, 28 Feb 2014 03:01:19 -0500
> Subject: [PATCH] fix vreq with error of -EBUSY fails 100 times too
> soon,
>  return EIO to td device layer.
> 
> 
> 1) all free list is consumed by vreq in one or two block that
>    is seted in bat entry.
> 2) vreq in fail queue, get a chance to run quickly, such as 90us.
> ---
>  tools/blktap2/drivers/tapdisk-vbd.c | 17 ++++++++++++++---
>  tools/blktap2/drivers/tapdisk-vbd.h |  1 +
>  2 files changed, 15 insertions(+), 3 deletions(-)
> 
> 
> diff --git a/tools/blktap2/drivers/tapdisk-vbd.c
> b/tools/blktap2/drivers/tapdisk-vbd.c
> index c665f27..529eb91 100644
> --- a/tools/blktap2/drivers/tapdisk-vbd.c
> +++ b/tools/blktap2/drivers/tapdisk-vbd.c
> @@ -1081,7 +1081,7 @@ tapdisk_vbd_check_state(td_vbd_t *vbd)
>   td_vbd_request_t *vreq, *tmp;
>  
>   tapdisk_vbd_for_each_request(vreq, tmp, &vbd->failed_requests)
> - if (vreq->num_retries >= TD_VBD_MAX_RETRIES)
> + if (vreq->num_retries >= TD_VBD_MAX_RETRIES && vreq->busy_looping !=
> 1 )
>   tapdisk_vbd_complete_vbd_request(vbd, vreq);
>  
>   if (!list_empty(&vbd->new_requests) ||
> @@ -1168,7 +1168,7 @@ tapdisk_vbd_complete_vbd_request(td_vbd_t *vbd,
> td_vbd_request_t *vreq)
>  {
>   if (!vreq->submitting && !vreq->secs_pending) {
>   if (vreq->status == BLKIF_RSP_ERROR &&
> -     vreq->num_retries < TD_VBD_MAX_RETRIES &&
> +     (vreq->num_retries < TD_VBD_MAX_RETRIES || vreq->busy_looping ==
> 1)&&
>       !td_flag_test(vbd->state, TD_VBD_DEAD) &&
>       !td_flag_test(vbd->state, TD_VBD_SHUTDOWN_REQUESTED))
>   tapdisk_vbd_move_request(vreq, &vbd->failed_requests);
> @@ -1450,17 +1450,28 @@ tapdisk_vbd_reissue_failed_requests(td_vbd_t
> *vbd)
>   gettimeofday(&now, NULL);
>  
>   tapdisk_vbd_for_each_request(vreq, tmp, &vbd->failed_requests) {
> + uint64_t delta = 0;
> +
>   if (vreq->secs_pending)
>   continue;
>  
>   if (td_flag_test(vbd->state, TD_VBD_SHUTDOWN_REQUESTED))
>   goto fail;
>  
> + if (vreq->num_retries > TD_VBD_MAX_RETRIES - 10) {
> + delta = (now.tv_sec - vreq->last_try.tv_sec) * 1000000\
> + + now.tv_usec - vreq->last_try.tv_usec;
> + if (delta * vreq->num_retries < TD_VBD_RETRY_INTERVAL)
> + vreq->busy_looping = 1;
> + else
> + vreq->busy_looping = 0;
> + }
> +
>   if (vreq->error != -EBUSY &&
>       now.tv_sec - vreq->last_try.tv_sec < TD_VBD_RETRY_INTERVAL)
>   continue;
>  
> - if (vreq->num_retries >= TD_VBD_MAX_RETRIES) {
> + if (vreq->num_retries >= TD_VBD_MAX_RETRIES && vreq->busy_looping !=
> 1) {
>   fail:
>   DBG(TLOG_INFO, "req %"PRIu64"retried %d times\n",
>       vreq->req.id, vreq->num_retries);
> diff --git a/tools/blktap2/drivers/tapdisk-vbd.h
> b/tools/blktap2/drivers/tapdisk-vbd.h
> index be084b2..9e5f5f6 100644
> --- a/tools/blktap2/drivers/tapdisk-vbd.h
> +++ b/tools/blktap2/drivers/tapdisk-vbd.h
> @@ -73,6 +73,7 @@ struct td_vbd_request {
>   int                         submitting;
>   int                         secs_pending;
>   int                         num_retries;
> + int                         busy_looping;
>   struct timeval              last_try;
>  
>   td_vbd_t                   *vbd;
> 
> 
> -- 
> 1.8.3.1
> 
> 
> 
> ______________________________________________________________________
> gordongong0350@xxxxxxxxx



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