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Message-ID: <ef12e2ff-5410-1f4e-e549-d99e37214257@linaro.org>
Date: Mon, 12 Jun 2023 13:55:26 +0100
From: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To: Ekansh Gupta <quic_ekangupt@...cinc.com>,
linux-arm-msm@...r.kernel.org
Cc: ekangupt@....qualcomm.com, gregkh@...uxfoundation.org,
linux-kernel@...r.kernel.org, fastrpc.upstream@....qualcomm.com,
quic_anane@...cinc.com
Subject: Re: [PATCH v1 1/2] misc: fastrpc: Add cached buffer support
On 09/06/2023 11:39, Ekansh Gupta wrote:
> FastRPC driver uses DMA API for region allocation for any buf_alloc
> request and the DMA region is unmap and freed once the usage is
> complete.
>
> Cached buffer support enables caching of certain types of buffers
> instead of freeing which help in reducing the overhead of DMA API
> call for every buffer allocation request.
Can you quanitfy this argument with some measurments?
what kind of savings/overhead are we seeing with this patch vs without?
--srini
>
> A list of cached buffer is maintained which will get reused when
> needed and this buffer list will get freed during device release.
>
> Co-developed-by: Anandu Krishnan E <quic_anane@...cinc.com>
> Signed-off-by: Anandu Krishnan E <quic_anane@...cinc.com>
> Signed-off-by: Ekansh Gupta <quic_ekangupt@...cinc.com>
> ---
> drivers/misc/fastrpc.c | 133 +++++++++++++++++++++++++++++++++++++-------
> include/uapi/misc/fastrpc.h | 8 +++
> 2 files changed, 122 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index 30d4d04..a961a66 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -41,6 +41,10 @@
> #define INIT_FILE_NAMELEN_MAX (128)
> #define FASTRPC_DEVICE_NAME "fastrpc"
>
> +/* Maximum buffers cached in cached buffer list */
> +#define FASTRPC_MAX_CACHED_BUFS (32)
> +#define FASTRPC_MAX_CACHE_BUF_SIZE (8*1024*1024)
> +
> /* Add memory to static PD pool, protection thru XPU */
> #define ADSP_MMAP_HEAP_ADDR 4
> /* MAP static DMA buffer on DSP User PD */
> @@ -195,6 +199,7 @@ struct fastrpc_buf {
> struct dma_buf *dmabuf;
> struct device *dev;
> void *virt;
> + u32 type;
> u64 phys;
> u64 size;
> /* Lock for dma buf attachments */
> @@ -293,6 +298,7 @@ struct fastrpc_user {
> struct list_head maps;
> struct list_head pending;
> struct list_head mmaps;
> + struct list_head cached_bufs;
>
> struct fastrpc_channel_ctx *cctx;
> struct fastrpc_session_ctx *sctx;
> @@ -300,6 +306,8 @@ struct fastrpc_user {
>
> int tgid;
> int pd;
> + /* total cached buffers */
> + u32 num_cached_buf;
> bool is_secure_dev;
> /* Lock for lists */
> spinlock_t lock;
> @@ -391,17 +399,95 @@ static int fastrpc_map_lookup(struct fastrpc_user *fl, int fd,
> return ret;
> }
>
> -static void fastrpc_buf_free(struct fastrpc_buf *buf)
> +static void __fastrpc_buf_free(struct fastrpc_buf *buf)
> {
> dma_free_coherent(buf->dev, buf->size, buf->virt,
> FASTRPC_PHYS(buf->phys));
> kfree(buf);
> }
>
> +static void fastrpc_cached_buf_list_add(struct fastrpc_buf *buf)
> +{
> + struct fastrpc_user *fl = buf->fl;
> +
> + if (buf->size < FASTRPC_MAX_CACHE_BUF_SIZE) {
> + spin_lock(&fl->lock);
> + if (fl->num_cached_buf > FASTRPC_MAX_CACHED_BUFS) {
> + spin_unlock(&fl->lock);
> + goto skip_buf_cache;
> + }
> +
> + list_add_tail(&buf->node, &fl->cached_bufs);
> + fl->num_cached_buf++;
> + buf->type = -1;
> + spin_unlock(&fl->lock);
> + }
> + return;
> +
> +skip_buf_cache:
> + __fastrpc_buf_free(buf);
> +}
> +
> +static void fastrpc_buf_free(struct fastrpc_buf *buf, bool cache)
> +{
> + if (cache)
> + fastrpc_cached_buf_list_add(buf);
> + else
> + __fastrpc_buf_free(buf);
> +}
> +
> +static inline bool fastrpc_get_cached_buf(struct fastrpc_user *fl,
> + size_t size, int buf_type, struct fastrpc_buf **obuf)
> +{
> + bool found = false;
> + struct fastrpc_buf *buf, *n, *cbuf = NULL;
> +
> + if (buf_type == USER_BUF)
> + return found;
> +
> + /* find the smallest buffer that fits in the cache */
> + spin_lock(&fl->lock);
> + list_for_each_entry_safe(buf, n, &fl->cached_bufs, node) {
> + if (buf->size >= size && (!cbuf || cbuf->size > buf->size))
> + cbuf = buf;
> + }
> + if (cbuf) {
> + list_del_init(&cbuf->node);
> + fl->num_cached_buf--;
> + }
> + spin_unlock(&fl->lock);
> + if (cbuf) {
> + cbuf->type = buf_type;
> + *obuf = cbuf;
> + found = true;
> + }
> +
> + return found;
> +}
> +
> +static void fastrpc_cached_buf_list_free(struct fastrpc_user *fl)
> +{
> + struct fastrpc_buf *buf, *n, *free;
> +
> + do {
> + free = NULL;
> + spin_lock(&fl->lock);
> + list_for_each_entry_safe(buf, n, &fl->cached_bufs, node) {
> + list_del(&buf->node);
> + fl->num_cached_buf--;
> + free = buf;
> + break;
> + }
> + spin_unlock(&fl->lock);
> + if (free)
> + fastrpc_buf_free(free, false);
> + } while (free);
> +}
> +
> static int __fastrpc_buf_alloc(struct fastrpc_user *fl, struct device *dev,
> u64 size, struct fastrpc_buf **obuf)
> {
> - struct fastrpc_buf *buf;
> + struct fastrpc_buf *buf = NULL;
>
> buf = kzalloc(sizeof(*buf), GFP_KERNEL);
> if (!buf)
> @@ -432,16 +518,23 @@ static int __fastrpc_buf_alloc(struct fastrpc_user *fl, struct device *dev,
> }
>
> static int fastrpc_buf_alloc(struct fastrpc_user *fl, struct device *dev,
> - u64 size, struct fastrpc_buf **obuf)
> + u64 size, u32 buf_type, struct fastrpc_buf **obuf)
> {
> int ret;
> struct fastrpc_buf *buf;
>
> + if (fastrpc_get_cached_buf(fl, size, buf_type, obuf))
> + return 0;
> ret = __fastrpc_buf_alloc(fl, dev, size, obuf);
> - if (ret)
> - return ret;
> + if (ret == -ENOMEM) {
> + fastrpc_cached_buf_list_free(fl);
> + ret = __fastrpc_buf_alloc(fl, dev, size, obuf);
> + if (ret)
> + return ret;
> + }
>
> buf = *obuf;
> + buf->type = buf_type;
>
> if (fl->sctx && fl->sctx->sid)
> buf->phys += ((u64)fl->sctx->sid << 32);
> @@ -490,7 +583,7 @@ static void fastrpc_context_free(struct kref *ref)
> fastrpc_map_put(ctx->maps[i]);
>
> if (ctx->buf)
> - fastrpc_buf_free(ctx->buf);
> + fastrpc_buf_free(ctx->buf, true);
>
> spin_lock_irqsave(&cctx->lock, flags);
> idr_remove(&cctx->ctx_idr, ctx->ctxid >> 4);
> @@ -674,7 +767,7 @@ static void fastrpc_release(struct dma_buf *dmabuf)
> {
> struct fastrpc_buf *buffer = dmabuf->priv;
>
> - fastrpc_buf_free(buffer);
> + fastrpc_buf_free(buffer, false);
> }
>
> static int fastrpc_dma_buf_attach(struct dma_buf *dmabuf,
> @@ -951,7 +1044,7 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx)
>
> ctx->msg_sz = pkt_size;
>
> - err = fastrpc_buf_alloc(ctx->fl, dev, pkt_size, &ctx->buf);
> + err = fastrpc_buf_alloc(ctx->fl, dev, pkt_size, METADATA_BUF, &ctx->buf);
> if (err)
> return err;
>
> @@ -1334,7 +1427,7 @@ static int fastrpc_init_create_static_process(struct fastrpc_user *fl,
> fl->cctx->remote_heap->phys, fl->cctx->remote_heap->size, err);
> }
> err_map:
> - fastrpc_buf_free(fl->cctx->remote_heap);
> + fastrpc_buf_free(fl->cctx->remote_heap, false);
> err_name:
> kfree(name);
> err:
> @@ -1403,7 +1496,7 @@ static int fastrpc_init_create_process(struct fastrpc_user *fl,
> memlen = ALIGN(max(INIT_FILELEN_MAX, (int)init.filelen * 4),
> 1024 * 1024);
> err = fastrpc_buf_alloc(fl, fl->sctx->dev, memlen,
> - &imem);
> + INITMEM_BUF, &imem);
> if (err)
> goto err_alloc;
>
> @@ -1450,7 +1543,7 @@ static int fastrpc_init_create_process(struct fastrpc_user *fl,
>
> err_invoke:
> fl->init_mem = NULL;
> - fastrpc_buf_free(imem);
> + fastrpc_buf_free(imem, false);
> err_alloc:
> fastrpc_map_put(map);
> err:
> @@ -1521,7 +1614,7 @@ static int fastrpc_device_release(struct inode *inode, struct file *file)
> spin_unlock_irqrestore(&cctx->lock, flags);
>
> if (fl->init_mem)
> - fastrpc_buf_free(fl->init_mem);
> + fastrpc_buf_free(fl->init_mem, false);
>
> list_for_each_entry_safe(ctx, n, &fl->pending, node) {
> list_del(&ctx->node);
> @@ -1533,9 +1626,10 @@ static int fastrpc_device_release(struct inode *inode, struct file *file)
>
> list_for_each_entry_safe(buf, b, &fl->mmaps, node) {
> list_del(&buf->node);
> - fastrpc_buf_free(buf);
> + fastrpc_buf_free(buf, false);
> }
>
> + fastrpc_cached_buf_list_free(fl);
> fastrpc_session_free(cctx, fl->sctx);
> fastrpc_channel_ctx_put(cctx);
>
> @@ -1570,6 +1664,7 @@ static int fastrpc_device_open(struct inode *inode, struct file *filp)
> INIT_LIST_HEAD(&fl->maps);
> INIT_LIST_HEAD(&fl->mmaps);
> INIT_LIST_HEAD(&fl->user);
> + INIT_LIST_HEAD(&fl->cached_bufs);
> fl->tgid = current->tgid;
> fl->cctx = cctx;
> fl->is_secure_dev = fdevice->secure;
> @@ -1600,7 +1695,7 @@ static int fastrpc_dmabuf_alloc(struct fastrpc_user *fl, char __user *argp)
> if (copy_from_user(&bp, argp, sizeof(bp)))
> return -EFAULT;
>
> - err = fastrpc_buf_alloc(fl, fl->sctx->dev, bp.size, &buf);
> + err = fastrpc_buf_alloc(fl, fl->sctx->dev, bp.size, USER_BUF, &buf);
> if (err)
> return err;
> exp_info.ops = &fastrpc_dma_buf_ops;
> @@ -1610,7 +1705,7 @@ static int fastrpc_dmabuf_alloc(struct fastrpc_user *fl, char __user *argp)
> buf->dmabuf = dma_buf_export(&exp_info);
> if (IS_ERR(buf->dmabuf)) {
> err = PTR_ERR(buf->dmabuf);
> - fastrpc_buf_free(buf);
> + fastrpc_buf_free(buf, false);
> return err;
> }
>
> @@ -1805,7 +1900,7 @@ static int fastrpc_req_munmap_impl(struct fastrpc_user *fl, struct fastrpc_buf *
> spin_lock(&fl->lock);
> list_del(&buf->node);
> spin_unlock(&fl->lock);
> - fastrpc_buf_free(buf);
> + fastrpc_buf_free(buf, false);
> } else {
> dev_err(dev, "unmmap\tpt 0x%09lx ERROR\n", buf->raddr);
> }
> @@ -1866,7 +1961,7 @@ static int fastrpc_req_mmap(struct fastrpc_user *fl, char __user *argp)
> return -EINVAL;
> }
>
> - err = fastrpc_buf_alloc(fl, fl->sctx->dev, req.size, &buf);
> + err = fastrpc_buf_alloc(fl, fl->sctx->dev, req.size, USER_BUF, &buf);
> if (err) {
> dev_err(dev, "failed to allocate buffer\n");
> return err;
> @@ -1935,7 +2030,7 @@ static int fastrpc_req_mmap(struct fastrpc_user *fl, char __user *argp)
> err_assign:
> fastrpc_req_munmap_impl(fl, buf);
> err_invoke:
> - fastrpc_buf_free(buf);
> + fastrpc_buf_free(buf, false);
>
> return err;
> }
> @@ -2380,7 +2475,7 @@ static void fastrpc_rpmsg_remove(struct rpmsg_device *rpdev)
> list_del(&buf->node);
>
> if (cctx->remote_heap)
> - fastrpc_buf_free(cctx->remote_heap);
> + fastrpc_buf_free(cctx->remote_heap, false);
>
> of_platform_depopulate(&rpdev->dev);
>
> diff --git a/include/uapi/misc/fastrpc.h b/include/uapi/misc/fastrpc.h
> index f33d914..91c7c4f 100644
> --- a/include/uapi/misc/fastrpc.h
> +++ b/include/uapi/misc/fastrpc.h
> @@ -64,6 +64,14 @@ enum fastrpc_proc_attr {
> FASTRPC_MODE_PRIVILEGED = (1 << 6),
> };
>
> + /* Types of fastrpc DMA bufs sent to DSP */
> + enum fastrpc_buf_type {
> + METADATA_BUF,
> + COPYDATA_BUF,
> + INITMEM_BUF,
> + USER_BUF,
> +};
> +
> /* Fastrpc attribute for memory protection of buffers */
> #define FASTRPC_ATTR_SECUREMAP (1)
>
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