summaryrefslogtreecommitdiff
path: root/drivers/dma-buf/dma-buf-sysfs-stats.h
diff options
context:
space:
mode:
authorHridya Valsaraju <hridya@google.com>2021-06-04 00:47:51 +0300
committerDaniel Vetter <daniel.vetter@ffwll.ch>2021-06-15 12:50:24 +0300
commitbdb8d06dfefd666d5981d884b535b04105869fcc (patch)
tree7e1e7d7099de0471456ef4f57cd5f0107181a2f8 /drivers/dma-buf/dma-buf-sysfs-stats.h
parentaae74ff9caa8de9a45ae2e46068c417817392a26 (diff)
downloadlinux-bdb8d06dfefd666d5981d884b535b04105869fcc.tar.xz
dmabuf: Add the capability to expose DMA-BUF stats in sysfs
Overview ======== The patch adds DMA-BUF statistics to /sys/kernel/dmabuf/buffers. It allows statistics to be enabled for each DMA-BUF in sysfs by enabling the config CONFIG_DMABUF_SYSFS_STATS. The following stats will be exposed by the interface: /sys/kernel/dmabuf/buffers/<inode_number>/exporter_name /sys/kernel/dmabuf/buffers/<inode_number>/size /sys/kernel/dmabuf/buffers/<inode_number>/attachments/<attach_uid>/device /sys/kernel/dmabuf/buffers/<inode_number>/attachments/<attach_uid>/map_counter The inode_number is unique for each DMA-BUF and was added earlier [1] in order to allow userspace to track DMA-BUF usage across different processes. Use Cases ========= The interface provides a way to gather DMA-BUF per-buffer statistics from production devices. These statistics will be used to derive DMA-BUF per-exporter stats and per-device usage stats for Android Bug reports. The corresponding userspace changes can be found at [2]. Telemetry tools will also capture this information(along with other memory metrics) periodically as well as on important events like a foreground app kill (which might have been triggered by Low Memory Killer). It will also contribute to provide a snapshot of the system memory usage on other events such as OOM kills and Application Not Responding events. Background ========== Currently, there are two existing interfaces that provide information about DMA-BUFs. 1) /sys/kernel/debug/dma_buf/bufinfo debugfs is however unsuitable to be mounted in production systems and cannot be considered as an alternative to the sysfs interface being proposed. 2) proc/<pid>/fdinfo/<fd> The proc/<pid>/fdinfo/<fd> files expose information about DMA-BUF fds. However, the existing procfs interfaces can only provide information about the buffers for which processes hold fds or have the buffers mmapped into their address space. Since the procfs interfaces alone cannot provide a full picture of all DMA-BUFs in the system, there is the need for an alternate interface to provide this information on production systems. The patch contains the following major improvements over v1: 1) Each attachment is represented by its own directory to allow creating a symlink to the importing device and to also provide room for future expansion. 2) The number of distinct mappings of each attachment is exposed in a separate file. 3) The per-buffer statistics are now in /sys/kernel/dmabuf/buffers inorder to make the interface expandable in future. All of the improvements above are based on suggestions/feedback from Daniel Vetter and Christian König. A shell script that can be run on a classic Linux environment to read out the DMA-BUF statistics can be found at [3](suggested by John Stultz). [1]: https://lore.kernel.org/patchwork/patch/1088791/ [2]: https://android-review.googlesource.com/q/topic:%22dmabuf-sysfs%22+(status:open%20OR%20status:merged) [3]: https://android-review.googlesource.com/c/platform/system/memory/libmeminfo/+/1549734 Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Hridya Valsaraju <hridya@google.com> Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20210603214758.2955251-1-hridya@google.com
Diffstat (limited to 'drivers/dma-buf/dma-buf-sysfs-stats.h')
-rw-r--r--drivers/dma-buf/dma-buf-sysfs-stats.h62
1 files changed, 62 insertions, 0 deletions
diff --git a/drivers/dma-buf/dma-buf-sysfs-stats.h b/drivers/dma-buf/dma-buf-sysfs-stats.h
new file mode 100644
index 000000000000..5f4703249117
--- /dev/null
+++ b/drivers/dma-buf/dma-buf-sysfs-stats.h
@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * DMA-BUF sysfs statistics.
+ *
+ * Copyright (C) 2021 Google LLC.
+ */
+
+#ifndef _DMA_BUF_SYSFS_STATS_H
+#define _DMA_BUF_SYSFS_STATS_H
+
+#ifdef CONFIG_DMABUF_SYSFS_STATS
+
+int dma_buf_init_sysfs_statistics(void);
+void dma_buf_uninit_sysfs_statistics(void);
+
+int dma_buf_stats_setup(struct dma_buf *dmabuf);
+int dma_buf_attach_stats_setup(struct dma_buf_attachment *attach,
+ unsigned int uid);
+static inline void dma_buf_update_attachment_map_count(struct dma_buf_attachment *attach,
+ int delta)
+{
+ struct dma_buf_attach_sysfs_entry *entry = attach->sysfs_entry;
+
+ entry->map_counter += delta;
+}
+void dma_buf_stats_teardown(struct dma_buf *dmabuf);
+void dma_buf_attach_stats_teardown(struct dma_buf_attachment *attach);
+static inline unsigned int dma_buf_update_attach_uid(struct dma_buf *dmabuf)
+{
+ struct dma_buf_sysfs_entry *entry = dmabuf->sysfs_entry;
+
+ return entry->attachment_uid++;
+}
+#else
+
+static inline int dma_buf_init_sysfs_statistics(void)
+{
+ return 0;
+}
+
+static inline void dma_buf_uninit_sysfs_statistics(void) {}
+
+static inline int dma_buf_stats_setup(struct dma_buf *dmabuf)
+{
+ return 0;
+}
+static inline int dma_buf_attach_stats_setup(struct dma_buf_attachment *attach,
+ unsigned int uid)
+{
+ return 0;
+}
+
+static inline void dma_buf_stats_teardown(struct dma_buf *dmabuf) {}
+static inline void dma_buf_attach_stats_teardown(struct dma_buf_attachment *attach) {}
+static inline void dma_buf_update_attachment_map_count(struct dma_buf_attachment *attach,
+ int delta) {}
+static inline unsigned int dma_buf_update_attach_uid(struct dma_buf *dmabuf)
+{
+ return 0;
+}
+#endif
+#endif // _DMA_BUF_SYSFS_STATS_H