[sheepdog] what is sheepdog-ng

陈李粮 1446130 at qq.com
Wed Jul 29 04:17:45 CEST 2015


what is sheepdog-ng?




------------------ Original ------------------
From:  "sheepdog-request";<sheepdog-request at lists.wpkg.org>;
Date:  Tue, Jul 28, 2015 06:00 PM
To:  "sheepdog"<sheepdog at lists.wpkg.org>; 

Subject:  sheepdog Digest, Vol 70, Issue 33



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Today's Topics:

   1. Re: [Qemu-devel] [PATCH] sheepdog: serialize requests to
      overwrapping area (Vasiliy Tolstov)
   2. Re: [Qemu-devel] [PATCH] sheepdog: serialize requests to
      overwrapping area (Jeff Cody)
   3. Re: [PATCH] sheepdog: serialize requests to overwrapping area
      (Liu Yuan)
   4. Re: [PATCH] sheepdog: serialize requests to overwrapping area
      (Liu Yuan)


----------------------------------------------------------------------

Message: 1
Date: Mon, 27 Jul 2015 18:36:08 +0300
From: Vasiliy Tolstov <v.tolstov at selfip.ru>
To: Jeff Cody <jcody at redhat.com>
Cc: Kevin Wolf <kwolf at redhat.com>, sheepdog at lists.wpkg.org, Hitoshi
	Mitake <mitake.hitoshi at lab.ntt.co.jp>, qemu-devel at nongnu.org, Stefan
	Hajnoczi <stefanha at redhat.com>, Teruaki Ishizaki
	<ishizaki.teruaki at lab.ntt.co.jp>
Subject: Re: [sheepdog] [Qemu-devel] [PATCH] sheepdog: serialize
	requests to	overwrapping area
Message-ID:
	<CACaajQt_fzqgKts7RnqDvxFeuwFzQ6AHie1+TSXiye0x=di11A at mail.gmail.com>
Content-Type: text/plain; charset=UTF-8

2015-07-27 18:23 GMT+03:00 Jeff Cody <jcody at redhat.com>:
> Thanks, applied to my block branch:
> https://github.com/codyprime/qemu-kvm-jtc/tree/block


Thanks! Waiting for adding to qemu rc =)

-- 
Vasiliy Tolstov,
e-mail: v.tolstov at selfip.ru


------------------------------

Message: 2
Date: Mon, 27 Jul 2015 11:23:02 -0400
From: Jeff Cody <jcody at redhat.com>
To: Hitoshi Mitake <mitake.hitoshi at lab.ntt.co.jp>
Cc: Kevin Wolf <kwolf at redhat.com>, sheepdog at lists.wpkg.org,
	qemu-devel at nongnu.org, Stefan Hajnoczi <stefanha at redhat.com>, Teruaki
	Ishizaki <ishizaki.teruaki at lab.ntt.co.jp>
Subject: Re: [sheepdog] [Qemu-devel] [PATCH] sheepdog: serialize
	requests to overwrapping area
Message-ID: <20150727152302.GH21772 at localhost.localdomain>
Content-Type: text/plain; charset=us-ascii

On Sat, Jul 18, 2015 at 01:44:24AM +0900, Hitoshi Mitake wrote:
> Current sheepdog driver only serializes create requests in oid
> unit. This mechanism isn't enough for handling requests to
> overwrapping area spanning multiple oids, so it can result bugs like
> below:
> https://bugs.launchpad.net/sheepdog-project/+bug/1456421
> 
> This patch adds a new serialization mechanism for the problem. The
> difference from the old one is:
> 1. serialize entire aiocb if their targetting areas overwrap
> 2. serialize all requests (read, write, and discard), not only creates
> 
> This patch also removes the old mechanism because the new one can be
> an alternative.
> 
> Cc: Kevin Wolf <kwolf at redhat.com>
> Cc: Stefan Hajnoczi <stefanha at redhat.com>
> Cc: Teruaki Ishizaki <ishizaki.teruaki at lab.ntt.co.jp>
> Cc: Vasiliy Tolstov <v.tolstov at selfip.ru>
> Signed-off-by: Hitoshi Mitake <mitake.hitoshi at lab.ntt.co.jp>
> ---
>  block/sheepdog.c | 152 ++++++++++++++++++++++++++-----------------------------
>  1 file changed, 71 insertions(+), 81 deletions(-)
> 
> diff --git a/block/sheepdog.c b/block/sheepdog.c
> index bd7cbed..9585beb 100644
> --- a/block/sheepdog.c
> +++ b/block/sheepdog.c
> @@ -318,6 +318,10 @@ enum AIOCBState {
>      AIOCB_DISCARD_OBJ,
>  };
>  
> +#define AIOCBOverwrapping(x, y)                                 \
> +    (!(x->max_affect_data_idx < y->min_affect_data_idx          \
> +       || y->max_affect_data_idx < x->min_affect_data_idx))
> +
>  struct SheepdogAIOCB {
>      BlockAIOCB common;
>  
> @@ -334,6 +338,11 @@ struct SheepdogAIOCB {
>  
>      bool cancelable;
>      int nr_pending;
> +
> +    uint32_t min_affect_data_idx;
> +    uint32_t max_affect_data_idx;
> +
> +    QLIST_ENTRY(SheepdogAIOCB) aiocb_siblings;
>  };
>  
>  typedef struct BDRVSheepdogState {
> @@ -362,8 +371,10 @@ typedef struct BDRVSheepdogState {
>  
>      /* Every aio request must be linked to either of these queues. */
>      QLIST_HEAD(inflight_aio_head, AIOReq) inflight_aio_head;
> -    QLIST_HEAD(pending_aio_head, AIOReq) pending_aio_head;
>      QLIST_HEAD(failed_aio_head, AIOReq) failed_aio_head;
> +
> +    CoQueue overwrapping_queue;
> +    QLIST_HEAD(inflight_aiocb_head, SheepdogAIOCB) inflight_aiocb_head;
>  } BDRVSheepdogState;
>  
>  static const char * sd_strerror(int err)
> @@ -498,13 +509,7 @@ static void sd_aio_cancel(BlockAIOCB *blockacb)
>      AIOReq *aioreq, *next;
>  
>      if (sd_acb_cancelable(acb)) {
> -        /* Remove outstanding requests from pending and failed queues.  */
> -        QLIST_FOREACH_SAFE(aioreq, &s->pending_aio_head, aio_siblings,
> -                           next) {
> -            if (aioreq->aiocb == acb) {
> -                free_aio_req(s, aioreq);
> -            }
> -        }
> +        /* Remove outstanding requests from failed queue.  */
>          QLIST_FOREACH_SAFE(aioreq, &s->failed_aio_head, aio_siblings,
>                             next) {
>              if (aioreq->aiocb == acb) {
> @@ -529,6 +534,10 @@ static SheepdogAIOCB *sd_aio_setup(BlockDriverState *bs, QEMUIOVector *qiov,
>                                     int64_t sector_num, int nb_sectors)
>  {
>      SheepdogAIOCB *acb;
> +    uint32_t object_size;
> +    BDRVSheepdogState *s = bs->opaque;
> +
> +    object_size = (UINT32_C(1) << s->inode.block_size_shift);
>  
>      acb = qemu_aio_get(&sd_aiocb_info, bs, NULL, NULL);
>  
> @@ -542,6 +551,11 @@ static SheepdogAIOCB *sd_aio_setup(BlockDriverState *bs, QEMUIOVector *qiov,
>      acb->coroutine = qemu_coroutine_self();
>      acb->ret = 0;
>      acb->nr_pending = 0;
> +
> +    acb->min_affect_data_idx = acb->sector_num * BDRV_SECTOR_SIZE / object_size;
> +    acb->max_affect_data_idx = (acb->sector_num * BDRV_SECTOR_SIZE +
> +                              acb->nb_sectors * BDRV_SECTOR_SIZE) / object_size;
> +
>      return acb;
>  }
>  
> @@ -703,38 +717,6 @@ static int reload_inode(BDRVSheepdogState *s, uint32_t snapid, const char *tag);
>  static int get_sheep_fd(BDRVSheepdogState *s, Error **errp);
>  static void co_write_request(void *opaque);
>  
> -static AIOReq *find_pending_req(BDRVSheepdogState *s, uint64_t oid)
> -{
> -    AIOReq *aio_req;
> -
> -    QLIST_FOREACH(aio_req, &s->pending_aio_head, aio_siblings) {
> -        if (aio_req->oid == oid) {
> -            return aio_req;
> -        }
> -    }
> -
> -    return NULL;
> -}
> -
> -/*
> - * This function searchs pending requests to the object `oid', and
> - * sends them.
> - */
> -static void coroutine_fn send_pending_req(BDRVSheepdogState *s, uint64_t oid)
> -{
> -    AIOReq *aio_req;
> -    SheepdogAIOCB *acb;
> -
> -    while ((aio_req = find_pending_req(s, oid)) != NULL) {
> -        acb = aio_req->aiocb;
> -        /* move aio_req from pending list to inflight one */
> -        QLIST_REMOVE(aio_req, aio_siblings);
> -        QLIST_INSERT_HEAD(&s->inflight_aio_head, aio_req, aio_siblings);
> -        add_aio_request(s, aio_req, acb->qiov->iov, acb->qiov->niov,
> -                        acb->aiocb_type);
> -    }
> -}
> -
>  static coroutine_fn void reconnect_to_sdog(void *opaque)
>  {
>      BDRVSheepdogState *s = opaque;
> @@ -840,12 +822,6 @@ static void coroutine_fn aio_read_response(void *opaque)
>                  s->max_dirty_data_idx = MAX(idx, s->max_dirty_data_idx);
>                  s->min_dirty_data_idx = MIN(idx, s->min_dirty_data_idx);
>              }
> -            /*
> -             * Some requests may be blocked because simultaneous
> -             * create requests are not allowed, so we search the
> -             * pending requests here.
> -             */
> -            send_pending_req(s, aio_req->oid);
>          }
>          break;
>      case AIOCB_READ_UDATA:
> @@ -1341,30 +1317,6 @@ out:
>      return ret;
>  }
>  
> -/* Return true if the specified request is linked to the pending list. */
> -static bool check_simultaneous_create(BDRVSheepdogState *s, AIOReq *aio_req)
> -{
> -    AIOReq *areq;
> -    QLIST_FOREACH(areq, &s->inflight_aio_head, aio_siblings) {
> -        if (areq != aio_req && areq->oid == aio_req->oid) {
> -            /*
> -             * Sheepdog cannot handle simultaneous create requests to the same
> -             * object, so we cannot send the request until the previous request
> -             * finishes.
> -             */
> -            DPRINTF("simultaneous create to %" PRIx64 "\n", aio_req->oid);
> -            aio_req->flags = 0;
> -            aio_req->base_oid = 0;
> -            aio_req->create = false;
> -            QLIST_REMOVE(aio_req, aio_siblings);
> -            QLIST_INSERT_HEAD(&s->pending_aio_head, aio_req, aio_siblings);
> -            return true;
> -        }
> -    }
> -
> -    return false;
> -}
> -
>  static void coroutine_fn resend_aioreq(BDRVSheepdogState *s, AIOReq *aio_req)
>  {
>      SheepdogAIOCB *acb = aio_req->aiocb;
> @@ -1379,10 +1331,6 @@ static void coroutine_fn resend_aioreq(BDRVSheepdogState *s, AIOReq *aio_req)
>              goto out;
>          }
>  
> -        if (check_simultaneous_create(s, aio_req)) {
> -            return;
> -        }
> -
>          if (s->inode.data_vdi_id[idx]) {
>              aio_req->base_oid = vid_to_data_oid(s->inode.data_vdi_id[idx], idx);
>              aio_req->flags |= SD_FLAG_CMD_COW;
> @@ -1458,8 +1406,8 @@ static int sd_open(BlockDriverState *bs, QDict *options, int flags,
>      filename = qemu_opt_get(opts, "filename");
>  
>      QLIST_INIT(&s->inflight_aio_head);
> -    QLIST_INIT(&s->pending_aio_head);
>      QLIST_INIT(&s->failed_aio_head);
> +    QLIST_INIT(&s->inflight_aiocb_head);
>      s->fd = -1;
>  
>      memset(vdi, 0, sizeof(vdi));
> @@ -1524,6 +1472,7 @@ static int sd_open(BlockDriverState *bs, QDict *options, int flags,
>      bs->total_sectors = s->inode.vdi_size / BDRV_SECTOR_SIZE;
>      pstrcpy(s->name, sizeof(s->name), vdi);
>      qemu_co_mutex_init(&s->lock);
> +    qemu_co_queue_init(&s->overwrapping_queue);
>      qemu_opts_del(opts);
>      g_free(buf);
>      return 0;
> @@ -2195,12 +2144,6 @@ static int coroutine_fn sd_co_rw_vector(void *p)
>                                  old_oid, done);
>          QLIST_INSERT_HEAD(&s->inflight_aio_head, aio_req, aio_siblings);
>  
> -        if (create) {
> -            if (check_simultaneous_create(s, aio_req)) {
> -                goto done;
> -            }
> -        }
> -
>          add_aio_request(s, aio_req, acb->qiov->iov, acb->qiov->niov,
>                          acb->aiocb_type);
>      done:
> @@ -2215,6 +2158,20 @@ out:
>      return 1;
>  }
>  
> +static bool check_overwrapping_aiocb(BDRVSheepdogState *s, SheepdogAIOCB *aiocb)
> +{
> +    SheepdogAIOCB *cb;
> +
> +    QLIST_FOREACH(cb, &s->inflight_aiocb_head, aiocb_siblings) {
> +        if (AIOCBOverwrapping(aiocb, cb)) {
> +            return true;
> +        }
> +    }
> +
> +    QLIST_INSERT_HEAD(&s->inflight_aiocb_head, aiocb, aiocb_siblings);
> +    return false;
> +}
> +
>  static coroutine_fn int sd_co_writev(BlockDriverState *bs, int64_t sector_num,
>                          int nb_sectors, QEMUIOVector *qiov)
>  {
> @@ -2234,14 +2191,25 @@ static coroutine_fn int sd_co_writev(BlockDriverState *bs, int64_t sector_num,
>      acb->aio_done_func = sd_write_done;
>      acb->aiocb_type = AIOCB_WRITE_UDATA;
>  
> +retry:
> +    if (check_overwrapping_aiocb(s, acb)) {
> +        qemu_co_queue_wait(&s->overwrapping_queue);
> +        goto retry;
> +    }
> +
>      ret = sd_co_rw_vector(acb);
>      if (ret <= 0) {
> +        QLIST_REMOVE(acb, aiocb_siblings);
> +        qemu_co_queue_restart_all(&s->overwrapping_queue);
>          qemu_aio_unref(acb);
>          return ret;
>      }
>  
>      qemu_coroutine_yield();
>  
> +    QLIST_REMOVE(acb, aiocb_siblings);
> +    qemu_co_queue_restart_all(&s->overwrapping_queue);
> +
>      return acb->ret;
>  }
>  
> @@ -2250,19 +2218,30 @@ static coroutine_fn int sd_co_readv(BlockDriverState *bs, int64_t sector_num,
>  {
>      SheepdogAIOCB *acb;
>      int ret;
> +    BDRVSheepdogState *s = bs->opaque;
>  
>      acb = sd_aio_setup(bs, qiov, sector_num, nb_sectors);
>      acb->aiocb_type = AIOCB_READ_UDATA;
>      acb->aio_done_func = sd_finish_aiocb;
>  
> +retry:
> +    if (check_overwrapping_aiocb(s, acb)) {
> +        qemu_co_queue_wait(&s->overwrapping_queue);
> +        goto retry;
> +    }
> +
>      ret = sd_co_rw_vector(acb);
>      if (ret <= 0) {
> +        QLIST_REMOVE(acb, aiocb_siblings);
> +        qemu_co_queue_restart_all(&s->overwrapping_queue);
>          qemu_aio_unref(acb);
>          return ret;
>      }
>  
>      qemu_coroutine_yield();
>  
> +    QLIST_REMOVE(acb, aiocb_siblings);
> +    qemu_co_queue_restart_all(&s->overwrapping_queue);
>      return acb->ret;
>  }
>  
> @@ -2610,14 +2589,25 @@ static coroutine_fn int sd_co_discard(BlockDriverState *bs, int64_t sector_num,
>      acb->aiocb_type = AIOCB_DISCARD_OBJ;
>      acb->aio_done_func = sd_finish_aiocb;
>  
> +retry:
> +    if (check_overwrapping_aiocb(s, acb)) {
> +        qemu_co_queue_wait(&s->overwrapping_queue);
> +        goto retry;
> +    }
> +
>      ret = sd_co_rw_vector(acb);
>      if (ret <= 0) {
> +        QLIST_REMOVE(acb, aiocb_siblings);
> +        qemu_co_queue_restart_all(&s->overwrapping_queue);
>          qemu_aio_unref(acb);
>          return ret;
>      }
>  
>      qemu_coroutine_yield();
>  
> +    QLIST_REMOVE(acb, aiocb_siblings);
> +    qemu_co_queue_restart_all(&s->overwrapping_queue);
> +
>      return acb->ret;
>  }
>  
> -- 
> 1.9.1
> 
>

Thanks, applied to my block branch:
https://github.com/codyprime/qemu-kvm-jtc/tree/block


Jeff



------------------------------

Message: 3
Date: Tue, 28 Jul 2015 16:50:08 +0800
From: Liu Yuan <namei.unix at gmail.com>
To: Hitoshi Mitake <mitake.hitoshi at lab.ntt.co.jp>
Cc: Kevin Wolf <kwolf at redhat.com>, sheepdog at lists.wpkg.org,
	qemu-devel at nongnu.org, Stefan Hajnoczi <stefanha at redhat.com>, Teruaki
	Ishizaki <ishizaki.teruaki at lab.ntt.co.jp>
Subject: Re: [sheepdog] [PATCH] sheepdog: serialize requests to
	overwrapping area
Message-ID: <20150728085008.GA4291 at ubuntu-trusty>
Content-Type: text/plain; charset=us-ascii

On Sat, Jul 18, 2015 at 01:44:24AM +0900, Hitoshi Mitake wrote:
> Current sheepdog driver only serializes create requests in oid
> unit. This mechanism isn't enough for handling requests to
> overwrapping area spanning multiple oids, so it can result bugs like
> below:
> https://bugs.launchpad.net/sheepdog-project/+bug/1456421

I'm a bit late to review the patch since I'm not on the cc list, but I'd like to
get the idea how the mentioned bug relates to the serialization of requests?

The mentioned bug looks to me more a bug of sheepdog because the create and
write request will only unref a single oid. The bug report is unclear about
why the object idx in inode becomes zero, at least not pointing that it relates
to QEMU.

But this patch assume QEMU send the requests the wrong way and just vaguely
says it is just wrong without reason.

What is overrapping requests? As far as I understand, the request that stride
over two objects will be split into two, to make sure all the requests fit the
sheepdog object size. Allow requests run concurrently on different SD objects is
way achieving high performance. This patch mutes this feature, to me, without a
decent reason. 

Probably I miss something hidden, but I'd like someone enlighten me about it
because this patch might slow down QEMU VM over sheepdog.

Thanks,
Yuan


------------------------------

Message: 4
Date: Tue, 28 Jul 2015 17:35:02 +0800
From: Liu Yuan <namei.unix at gmail.com>
To: Hitoshi Mitake <mitake.hitoshi at lab.ntt.co.jp>
Cc: Kevin Wolf <kwolf at redhat.com>, sheepdog at lists.wpkg.org, Jeff Cody
	<jcody at redhat.com>, qemu-devel at nongnu.org, Stefan Hajnoczi
	<stefanha at redhat.com>, Teruaki Ishizaki
	<ishizaki.teruaki at lab.ntt.co.jp>
Subject: Re: [sheepdog] [PATCH] sheepdog: serialize requests to
	overwrapping area
Message-ID: <20150728093502.GA8357 at ubuntu-trusty>
Content-Type: text/plain; charset=us-ascii

On Tue, Jul 28, 2015 at 04:50:08PM +0800, Liu Yuan wrote:
> On Sat, Jul 18, 2015 at 01:44:24AM +0900, Hitoshi Mitake wrote:
> > Current sheepdog driver only serializes create requests in oid
> > unit. This mechanism isn't enough for handling requests to
> > overwrapping area spanning multiple oids, so it can result bugs like
> > below:
> > https://bugs.launchpad.net/sheepdog-project/+bug/1456421
> 
> I'm a bit late to review the patch since I'm not on the cc list, but I'd like to
> get the idea how the mentioned bug relates to the serialization of requests?
> 
> The mentioned bug looks to me more a bug of sheepdog because the create and
> write request will only unref a single oid. The bug report is unclear about
> why the object idx in inode becomes zero, at least not pointing that it relates
> to QEMU.
> 
> But this patch assume QEMU send the requests the wrong way and just vaguely
> says it is just wrong without reason.
> 
> What is overrapping requests? As far as I understand, the request that stride
> over two objects will be split into two, to make sure all the requests fit the
> sheepdog object size. Allow requests run concurrently on different SD objects is
> way achieving high performance. This patch mutes this feature, to me, without a
> decent reason. 
> 
> Probably I miss something hidden, but I'd like someone enlighten me about it
> because this patch might slow down QEMU VM over sheepdog.
> 
> Thanks,
> Yuan

Cc Jeff


------------------------------

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