Message-ID: <CAFCwf13zp78dKKAU+KcWs+4jC+jdd5dU8n8N0NfHg+AXOGR5aw@mail.gmail.com>
Date:   Thu, 4 May 2023 09:12:40 +0300
From:   Oded Gabbay <ogabbay@...nel.org>
To:     Cai Huoqing <cai.huoqing@...ux.dev>
Cc:     Ohad Sharabi <osharabi@...ana.ai>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] accel/habanalabs: Make use of rhashtable

On Thu, May 4, 2023 at 6:00 AM Cai Huoqing <cai.huoqing@...ux.dev> wrote:
>
> On 30 4月 23 09:36:29, Oded Gabbay wrote:
> > On Fri, Apr 28, 2023 at 5:49 PM Cai Huoqing <cai.huoqing@...ux.dev> wrote:
> > >
> > > Using rhashtable to accelerate the search for userptr by address,
> > > instead of using a list.
> > >
> > > Preferably, the lookup complexity of a hash table is O(1).
> > >
> > > This patch will speedup the method
> > > hl_userptr_is_pinned by rhashtable_lookup_fast.
> > >
> > > Signed-off-by: Cai Huoqing <cai.huoqing@...ux.dev>
> >
> > Thanks for the patch, but the reason we never optimized this path is
> > because this code path is only relevant for Goya, which we don't want
> > to change the code for anymore.
> > For Gaudi we don't pin the memory in the host during submission. It is
> > done much earlier, when the user maps the memory to the device. The
> > code path in Gaudi is only in case the device is loaded with its MMU
> > disabled. This mode was used only for debug/bring-up of the ASIC many
> > years ago. As you can see in Gaudi2, that mode was dropped even for
>
> Do you mean that the userspace directly call HL_MEM_OP_MAP/HL_MEM_OP_UNMAP
> with a flag HL_MEM_USERPTR instead of pin host mem in submissmion?
Yes, correct.

>
> > debug/bring-up.
> >
> > Therefore, I prefer not to take this patch as validation for both
> > functionality and performance will take time which will be better
> > spent elsewhere.
> >
> > Thanks,
> > Oded
> >
> > > ---
> > > v1->v2:
> > > Use rhashtable_free_and_destroy in hl_userptr_delete_list.
> > >
> > >  .../habanalabs/common/command_submission.c    | 16 ++++++--
> > >  drivers/accel/habanalabs/common/habanalabs.h  | 19 +++++----
> > >  drivers/accel/habanalabs/common/memory.c      | 39 +++++++++++--------
> > >  drivers/accel/habanalabs/gaudi/gaudi.c        | 16 +++++---
> > >  drivers/accel/habanalabs/goya/goya.c          | 14 ++++---
> > >  5 files changed, 65 insertions(+), 39 deletions(-)
> > >
> > > diff --git a/drivers/accel/habanalabs/common/command_submission.c b/drivers/accel/habanalabs/common/command_submission.c
> > > index af9d2e22c6e7..35c2ab934396 100644
> > > --- a/drivers/accel/habanalabs/common/command_submission.c
> > > +++ b/drivers/accel/habanalabs/common/command_submission.c
> > > @@ -312,7 +312,7 @@ static int cs_parser(struct hl_fpriv *hpriv, struct hl_cs_job *job)
> > >         parser.job_id = job->id;
> > >
> > >         parser.hw_queue_id = job->hw_queue_id;
> > > -       parser.job_userptr_list = &job->userptr_list;
> > > +       parser.job_userptr_ht = &job->userptr_ht;
> > >         parser.patched_cb = NULL;
> > >         parser.user_cb = job->user_cb;
> > >         parser.user_cb_size = job->user_cb_size;
> > > @@ -351,7 +351,7 @@ static void hl_complete_job(struct hl_device *hdev, struct hl_cs_job *job)
> > >         struct hl_cs *cs = job->cs;
> > >
> > >         if (is_cb_patched(hdev, job)) {
> > > -               hl_userptr_delete_list(hdev, &job->userptr_list);
> > > +               hl_userptr_delete_list(hdev, &job->userptr_ht);
> > >
> > >                 /*
> > >                  * We might arrive here from rollback and patched CB wasn't
> > > @@ -1284,6 +1284,7 @@ struct hl_cs_job *hl_cs_allocate_job(struct hl_device *hdev,
> > >                 enum hl_queue_type queue_type, bool is_kernel_allocated_cb)
> > >  {
> > >         struct hl_cs_job *job;
> > > +       int rc;
> > >
> > >         job = kzalloc(sizeof(*job), GFP_ATOMIC);
> > >         if (!job)
> > > @@ -1296,13 +1297,20 @@ struct hl_cs_job *hl_cs_allocate_job(struct hl_device *hdev,
> > >         job->queue_type = queue_type;
> > >         job->is_kernel_allocated_cb = is_kernel_allocated_cb;
> > >
> > > -       if (is_cb_patched(hdev, job))
> > > -               INIT_LIST_HEAD(&job->userptr_list);
> > > +       if (is_cb_patched(hdev, job)) {
> > > +               rc = rhashtable_init(&job->userptr_ht, &hl_userptr_rht_params);
> > > +               if (rc)
> > > +                       goto free_job;
> > > +       }
> > >
> > >         if (job->queue_type == QUEUE_TYPE_EXT)
> > >                 INIT_WORK(&job->finish_work, job_wq_completion);
> > >
> > >         return job;
> > > +
> > > +free_job:
> > > +       kfree(job);
> > > +       return NULL;
> > >  }
> > >
> > >  static enum hl_cs_type hl_cs_get_cs_type(u32 cs_type_flags)
> > > diff --git a/drivers/accel/habanalabs/common/habanalabs.h b/drivers/accel/habanalabs/common/habanalabs.h
> > > index eaae69a9f817..9c876d1480d2 100644
> > > --- a/drivers/accel/habanalabs/common/habanalabs.h
> > > +++ b/drivers/accel/habanalabs/common/habanalabs.h
> > > @@ -19,6 +19,7 @@
> > >  #include <linux/dma-direction.h>
> > >  #include <linux/scatterlist.h>
> > >  #include <linux/hashtable.h>
> > > +#include <linux/rhashtable.h>
> > >  #include <linux/debugfs.h>
> > >  #include <linux/rwsem.h>
> > >  #include <linux/eventfd.h>
> > > @@ -540,6 +541,8 @@ struct hl_hints_range {
> > >         u64 end_addr;
> > >  };
> > >
> > > +extern const struct rhashtable_params hl_userptr_rht_params;
> > > +
> > >  /**
> > >   * struct asic_fixed_properties - ASIC specific immutable properties.
> > >   * @hw_queues_props: H/W queues properties.
> > > @@ -1915,7 +1918,7 @@ struct hl_ctx_mgr {
> > >  /**
> > >   * struct hl_userptr - memory mapping chunk information
> > >   * @vm_type: type of the VM.
> > > - * @job_node: linked-list node for hanging the object on the Job's list.
> > > + * @job_node: hashtable node for hanging the object on the Job's list.
> > >   * @pages: pointer to struct page array
> > >   * @npages: size of @pages array
> > >   * @sgt: pointer to the scatter-gather table that holds the pages.
> > > @@ -1928,7 +1931,7 @@ struct hl_ctx_mgr {
> > >   */
> > >  struct hl_userptr {
> > >         enum vm_type            vm_type; /* must be first */
> > > -       struct list_head        job_node;
> > > +       struct rhash_head       job_node;
> > >         struct page             **pages;
> > >         unsigned int            npages;
> > >         struct sg_table         *sgt;
> > > @@ -2028,7 +2031,7 @@ struct hl_cs {
> > >   * @patched_cb: in case of patching, this is internal CB which is submitted on
> > >   *             the queue instead of the CB we got from the IOCTL.
> > >   * @finish_work: workqueue object to run when job is completed.
> > > - * @userptr_list: linked-list of userptr mappings that belong to this job and
> > > + * @userptr_ht: hashtable of userptr mappings that belong to this job and
> > >   *                     wait for completion.
> > >   * @debugfs_list: node in debugfs list of command submission jobs.
> > >   * @refcount: reference counter for usage of the CS job.
> > > @@ -2056,7 +2059,7 @@ struct hl_cs_job {
> > >         struct hl_cb            *user_cb;
> > >         struct hl_cb            *patched_cb;
> > >         struct work_struct      finish_work;
> > > -       struct list_head        userptr_list;
> > > +       struct rhashtable       userptr_ht;
> > >         struct list_head        debugfs_list;
> > >         struct kref             refcount;
> > >         enum hl_queue_type      queue_type;
> > > @@ -2075,7 +2078,7 @@ struct hl_cs_job {
> > >   * @user_cb: the CB we got from the user.
> > >   * @patched_cb: in case of patching, this is internal CB which is submitted on
> > >   *             the queue instead of the CB we got from the IOCTL.
> > > - * @job_userptr_list: linked-list of userptr mappings that belong to the related
> > > + * @job_userptr_ht: hashtable of userptr mappings that belong to the related
> > >   *                     job and wait for completion.
> > >   * @cs_sequence: the sequence number of the related CS.
> > >   * @queue_type: the type of the H/W queue this job is submitted to.
> > > @@ -2098,7 +2101,7 @@ struct hl_cs_job {
> > >  struct hl_cs_parser {
> > >         struct hl_cb            *user_cb;
> > >         struct hl_cb            *patched_cb;
> > > -       struct list_head        *job_userptr_list;
> > > +       struct rhashtable       *job_userptr_ht;
> > >         u64                     cs_sequence;
> > >         enum hl_queue_type      queue_type;
> > >         u32                     ctx_id;
> > > @@ -3760,9 +3763,9 @@ int hl_pin_host_memory(struct hl_device *hdev, u64 addr, u64 size,
> > >                         struct hl_userptr *userptr);
> > >  void hl_unpin_host_memory(struct hl_device *hdev, struct hl_userptr *userptr);
> > >  void hl_userptr_delete_list(struct hl_device *hdev,
> > > -                               struct list_head *userptr_list);
> > > +                               struct rhashtable *userptr_ht);
> > >  bool hl_userptr_is_pinned(struct hl_device *hdev, u64 addr, u32 size,
> > > -                               struct list_head *userptr_list,
> > > +                               struct rhashtable *userptr_ht,
> > >                                 struct hl_userptr **userptr);
> > >
> > >  int hl_mmu_init(struct hl_device *hdev);
> > > diff --git a/drivers/accel/habanalabs/common/memory.c b/drivers/accel/habanalabs/common/memory.c
> > > index a7b6a273ce21..fa2104e33639 100644
> > > --- a/drivers/accel/habanalabs/common/memory.c
> > > +++ b/drivers/accel/habanalabs/common/memory.c
> > > @@ -23,6 +23,13 @@ MODULE_IMPORT_NS(DMA_BUF);
> > >
> > >  #define MEM_HANDLE_INVALID     ULONG_MAX
> > >
> > > +const struct rhashtable_params hl_userptr_rht_params = {
> > > +       .head_offset = offsetof(struct hl_userptr, job_node),
> > > +       .key_offset = offsetof(struct hl_userptr, addr),
> > > +       .key_len = sizeof(u64),
> > > +       .automatic_shrinking = true,
> > > +};
> > > +
> > >  static int allocate_timestamps_buffers(struct hl_fpriv *hpriv,
> > >                         struct hl_mem_in *args, u64 *handle);
> > >
> > > @@ -2483,7 +2490,6 @@ int hl_pin_host_memory(struct hl_device *hdev, u64 addr, u64 size,
> > >         userptr->size = size;
> > >         userptr->addr = addr;
> > >         userptr->dma_mapped = false;
> > > -       INIT_LIST_HEAD(&userptr->job_node);
> > >
> > >         rc = get_user_memory(hdev, addr, size, npages, start, offset,
> > >                                 userptr);
> > > @@ -2522,32 +2528,32 @@ void hl_unpin_host_memory(struct hl_device *hdev, struct hl_userptr *userptr)
> > >         unpin_user_pages_dirty_lock(userptr->pages, userptr->npages, true);
> > >         kvfree(userptr->pages);
> > >
> > > -       list_del(&userptr->job_node);
> > > -
> > >         sg_free_table(userptr->sgt);
> > >         kfree(userptr->sgt);
> > >  }
> > >
> > > +static void hl_userptr_free_cb(void *ptr, void *arg)
> > > +{
> > > +       struct hl_userptr *userptr = ptr;
> > > +       struct hl_device *hdev = (struct hl_device *)arg;
> > > +
> > > +       hl_unpin_host_memory(hdev, userptr);
> > > +       kfree(userptr);
> > > +}
> > > +
> > >  /**
> > >   * hl_userptr_delete_list() - clear userptr list.
> > >   * @hdev: pointer to the habanalabs device structure.
> > > - * @userptr_list: pointer to the list to clear.
> > > + * @userptr_ht: pointer to the hashtable to clear.
> > >   *
> > >   * This function does the following:
> > >   * - Iterates over the list and unpins the host memory and frees the userptr
> > >   *   structure.
> > >   */
> > >  void hl_userptr_delete_list(struct hl_device *hdev,
> > > -                               struct list_head *userptr_list)
> > > +                               struct rhashtable *userptr_ht)
> > >  {
> > > -       struct hl_userptr *userptr, *tmp;
> > > -
> > > -       list_for_each_entry_safe(userptr, tmp, userptr_list, job_node) {
> > > -               hl_unpin_host_memory(hdev, userptr);
> > > -               kfree(userptr);
> > > -       }
> > > -
> > > -       INIT_LIST_HEAD(userptr_list);
> > > +       rhashtable_free_and_destroy(userptr_ht, hl_userptr_free_cb, hdev);
> > >  }
> > >
> > >  /**
> > > @@ -2555,7 +2561,7 @@ void hl_userptr_delete_list(struct hl_device *hdev,
> > >   * @hdev: pointer to the habanalabs device structure.
> > >   * @addr: user address to check.
> > >   * @size: user block size to check.
> > > - * @userptr_list: pointer to the list to clear.
> > > + * @userptr_ht: pointer to the hashtable to clear.
> > >   * @userptr: pointer to userptr to check.
> > >   *
> > >   * This function does the following:
> > > @@ -2563,10 +2569,11 @@ void hl_userptr_delete_list(struct hl_device *hdev,
> > >   *   pinned. If so, returns true, otherwise returns false.
> > >   */
> > >  bool hl_userptr_is_pinned(struct hl_device *hdev, u64 addr,
> > > -                               u32 size, struct list_head *userptr_list,
> > > +                               u32 size, struct rhashtable *userptr_ht,
> > >                                 struct hl_userptr **userptr)
> > >  {
> > > -       list_for_each_entry((*userptr), userptr_list, job_node) {
> > > +       (*userptr) = rhashtable_lookup_fast(userptr_ht, &addr, hl_userptr_rht_params);
> > > +       if (*userptr) {
> > >                 if ((addr == (*userptr)->addr) && (size == (*userptr)->size))
> > >                         return true;
> > >         }
> > > diff --git a/drivers/accel/habanalabs/gaudi/gaudi.c b/drivers/accel/habanalabs/gaudi/gaudi.c
> > > index a29aa8f7b6f3..1e1433042413 100644
> > > --- a/drivers/accel/habanalabs/gaudi/gaudi.c
> > > +++ b/drivers/accel/habanalabs/gaudi/gaudi.c
> > > @@ -1031,7 +1031,7 @@ static int _gaudi_init_tpc_mem(struct hl_device *hdev,
> > >         }
> > >
> > >  free_job:
> > > -       hl_userptr_delete_list(hdev, &job->userptr_list);
> > > +       hl_userptr_delete_list(hdev, &job->userptr_ht);
> > >         hl_debugfs_remove_job(hdev, job);
> > >         kfree(job);
> > >         atomic_dec(&cb->cs_cnt);
> > > @@ -4901,7 +4901,7 @@ static int gaudi_pin_memory_before_cs(struct hl_device *hdev,
> > >         int rc;
> > >
> > >         if (hl_userptr_is_pinned(hdev, addr, le32_to_cpu(user_dma_pkt->tsize),
> > > -                       parser->job_userptr_list, &userptr))
> > > +                       parser->job_userptr_ht, &userptr))
> > >                 goto already_pinned;
> > >
> > >         userptr = kzalloc(sizeof(*userptr), GFP_KERNEL);
> > > @@ -4913,7 +4913,10 @@ static int gaudi_pin_memory_before_cs(struct hl_device *hdev,
> > >         if (rc)
> > >                 goto free_userptr;
> > >
> > > -       list_add_tail(&userptr->job_node, parser->job_userptr_list);
> > > +       rc = rhashtable_insert_fast(parser->job_userptr_ht,
> > > +                                   &userptr->job_node, hl_userptr_rht_params);
> > > +       if (rc)
> > > +               goto unpin_memory;
> > >
> > >         rc = hdev->asic_funcs->asic_dma_map_sgtable(hdev, userptr->sgt, dir);
> > >         if (rc) {
> > > @@ -4931,7 +4934,8 @@ static int gaudi_pin_memory_before_cs(struct hl_device *hdev,
> > >         return 0;
> > >
> > >  unpin_memory:
> > > -       list_del(&userptr->job_node);
> > > +       rhashtable_remove_fast(parser->job_userptr_ht,
> > > +                              &userptr->job_node, hl_userptr_rht_params);
> > >         hl_unpin_host_memory(hdev, userptr);
> > >  free_userptr:
> > >         kfree(userptr);
> > > @@ -5175,7 +5179,7 @@ static int gaudi_patch_dma_packet(struct hl_device *hdev,
> > >         if ((!skip_host_mem_pin) &&
> > >                 (!hl_userptr_is_pinned(hdev, addr,
> > >                                         le32_to_cpu(user_dma_pkt->tsize),
> > > -                                       parser->job_userptr_list, &userptr))) {
> > > +                                       parser->job_userptr_ht, &userptr))) {
> > >                 dev_err(hdev->dev, "Userptr 0x%llx + 0x%x NOT mapped\n",
> > >                                 addr, user_dma_pkt->tsize);
> > >                 return -EFAULT;
> > > @@ -5472,7 +5476,7 @@ static int gaudi_parse_cb_no_mmu(struct hl_device *hdev,
> > >
> > >  free_userptr:
> > >         if (rc)
> > > -               hl_userptr_delete_list(hdev, parser->job_userptr_list);
> > > +               hl_userptr_delete_list(hdev, parser->job_userptr_ht);
> > >         return rc;
> > >  }
> > >
> > > diff --git a/drivers/accel/habanalabs/goya/goya.c b/drivers/accel/habanalabs/goya/goya.c
> > > index fb0ac9df841a..bfcbb9e8b126 100644
> > > --- a/drivers/accel/habanalabs/goya/goya.c
> > > +++ b/drivers/accel/habanalabs/goya/goya.c
> > > @@ -3347,7 +3347,7 @@ static int goya_pin_memory_before_cs(struct hl_device *hdev,
> > >         int rc;
> > >
> > >         if (hl_userptr_is_pinned(hdev, addr, le32_to_cpu(user_dma_pkt->tsize),
> > > -                       parser->job_userptr_list, &userptr))
> > > +                       parser->job_userptr_ht, &userptr))
> > >                 goto already_pinned;
> > >
> > >         userptr = kzalloc(sizeof(*userptr), GFP_KERNEL);
> > > @@ -3359,7 +3359,10 @@ static int goya_pin_memory_before_cs(struct hl_device *hdev,
> > >         if (rc)
> > >                 goto free_userptr;
> > >
> > > -       list_add_tail(&userptr->job_node, parser->job_userptr_list);
> > > +       rc = rhashtable_insert_fast(parser->job_userptr_ht,
> > > +                                   &userptr->job_node, hl_userptr_rht_params);
> > > +       if (rc)
> > > +               goto unpin_memory;
> > >
> > >         rc = hdev->asic_funcs->asic_dma_map_sgtable(hdev, userptr->sgt, dir);
> > >         if (rc) {
> > > @@ -3377,7 +3380,8 @@ static int goya_pin_memory_before_cs(struct hl_device *hdev,
> > >         return 0;
> > >
> > >  unpin_memory:
> > > -       list_del(&userptr->job_node);
> > > +       rhashtable_remove_fast(parser->job_userptr_ht,
> > > +                              &userptr->job_node, hl_userptr_rht_params);
> > >         hl_unpin_host_memory(hdev, userptr);
> > >  free_userptr:
> > >         kfree(userptr);
> > > @@ -3806,7 +3810,7 @@ static int goya_patch_dma_packet(struct hl_device *hdev,
> > >         if ((!skip_host_mem_pin) &&
> > >                 (hl_userptr_is_pinned(hdev, addr,
> > >                         le32_to_cpu(user_dma_pkt->tsize),
> > > -                       parser->job_userptr_list, &userptr) == false)) {
> > > +                       parser->job_userptr_ht, &userptr) == false)) {
> > >                 dev_err(hdev->dev, "Userptr 0x%llx + 0x%x NOT mapped\n",
> > >                                 addr, user_dma_pkt->tsize);
> > >                 return -EFAULT;
> > > @@ -4104,7 +4108,7 @@ static int goya_parse_cb_no_mmu(struct hl_device *hdev,
> > >
> > >  free_userptr:
> > >         if (rc)
> > > -               hl_userptr_delete_list(hdev, parser->job_userptr_list);
> > > +               hl_userptr_delete_list(hdev, parser->job_userptr_ht);
> > >         return rc;
> > >  }
> > >
> > > --
> > > 2.34.1
> > >

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