[PATCH] drm/msm: Optimize GPU crashstate capture read path
Sharat Masetty
smasetty at codeaurora.org
Thu Nov 1 08:35:41 UTC 2018
When the userspace tries to read the crashstate dump, the read side
implementation in the driver currently ascii85 encodes all the binary
buffers and it does this each time the read system call is called.
A userspace tool like cat typically does a page by page read and the
number of read calls depends on the size of the data captured by the
driver. This is certainly not desirable and does not scale well with
large captures.
This patch starts off with moving the encoding part to the capture time,
that is when the GPU tries to recover after a hang. Now we only encode
once per buffer object and not per page read. With this there is an
immediate >10X speed improvement in crashstate save time.
The flip side however is that the GPU recovery time increases and this
negatively impacts the user experience, so this is handled by moving the
encoding part to a worker thread and only register with the dev_coredump
once the encoding of the buffers is complete.
Signed-off-by: Sharat Masetty <smasetty at codeaurora.org>
---
drivers/gpu/drm/msm/adreno/adreno_gpu.c | 35 +++----------
drivers/gpu/drm/msm/msm_gpu.c | 93 +++++++++++++++++++++++++++++++--
drivers/gpu/drm/msm/msm_gpu.h | 1 +
3 files changed, 98 insertions(+), 31 deletions(-)
diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
index 141062f..7441571 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
@@ -406,7 +406,7 @@ int adreno_gpu_state_get(struct msm_gpu *gpu, struct msm_gpu_state *state)
size = j + 1;
if (size) {
- state->ring[i].data = kmalloc(size << 2, GFP_KERNEL);
+ state->ring[i].data = kvmalloc(size << 2, GFP_KERNEL);
if (state->ring[i].data) {
memcpy(state->ring[i].data, gpu->rb[i]->start, size << 2);
state->ring[i].data_size = size << 2;
@@ -445,7 +445,7 @@ void adreno_gpu_state_destroy(struct msm_gpu_state *state)
int i;
for (i = 0; i < ARRAY_SIZE(state->ring); i++)
- kfree(state->ring[i].data);
+ kvfree(state->ring[i].data);
for (i = 0; state->bos && i < state->nr_bos; i++)
kvfree(state->bos[i].data);
@@ -475,34 +475,15 @@ int adreno_gpu_state_put(struct msm_gpu_state *state)
#if defined(CONFIG_DEBUG_FS) || defined(CONFIG_DEV_COREDUMP)
-static void adreno_show_object(struct drm_printer *p, u32 *ptr, int len)
+static void adreno_show_object(struct drm_printer *p, void *ptr)
{
- char out[ASCII85_BUFSZ];
- long l, datalen, i;
-
- if (!ptr || !len)
- return;
-
- /*
- * Only dump the non-zero part of the buffer - rarely will any data
- * completely fill the entire allocated size of the buffer
- */
- for (datalen = 0, i = 0; i < len >> 2; i++) {
- if (ptr[i])
- datalen = (i << 2) + 1;
- }
-
- /* Skip printing the object if it is empty */
- if (datalen == 0)
+ if (!ptr)
return;
- l = ascii85_encode_len(datalen);
-
drm_puts(p, " data: !!ascii85 |\n");
drm_puts(p, " ");
- for (i = 0; i < l; i++)
- drm_puts(p, ascii85_encode(ptr[i], out));
+ drm_puts(p, ptr);
drm_puts(p, "\n");
}
@@ -534,8 +515,7 @@ void adreno_show(struct msm_gpu *gpu, struct msm_gpu_state *state,
drm_printf(p, " wptr: %d\n", state->ring[i].wptr);
drm_printf(p, " size: %d\n", MSM_GPU_RINGBUFFER_SZ);
- adreno_show_object(p, state->ring[i].data,
- state->ring[i].data_size);
+ adreno_show_object(p, state->ring[i].data);
}
if (state->bos) {
@@ -546,8 +526,7 @@ void adreno_show(struct msm_gpu *gpu, struct msm_gpu_state *state,
state->bos[i].iova);
drm_printf(p, " size: %zd\n", state->bos[i].size);
- adreno_show_object(p, state->bos[i].data,
- state->bos[i].size);
+ adreno_show_object(p, state->bos[i].data);
}
}
diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index ff95848..d5533f1 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -21,6 +21,7 @@
#include "msm_fence.h"
#include <generated/utsrelease.h>
+#include <linux/ascii85.h>
#include <linux/string_helpers.h>
#include <linux/pm_opp.h>
#include <linux/devfreq.h>
@@ -375,9 +376,7 @@ static void msm_gpu_crashstate_capture(struct msm_gpu *gpu,
/* Set the active crash state to be dumped on failure */
gpu->crashstate = state;
- /* FIXME: Release the crashstate if this errors out? */
- dev_coredumpm(gpu->dev->dev, THIS_MODULE, gpu, 0, GFP_KERNEL,
- msm_gpu_devcoredump_read, msm_gpu_devcoredump_free);
+ schedule_work(&gpu->crashstate_work);
}
#else
static void msm_gpu_crashstate_capture(struct msm_gpu *gpu,
@@ -420,6 +419,93 @@ static void update_fences(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
static void retire_submits(struct msm_gpu *gpu);
+static char *msm_gpu_ascii85_encode_buf(u32 *src, size_t len)
+{
+ void *buf;
+ size_t buf_itr = 0, buffer_size;
+ char out[ASCII85_BUFSZ];
+ long l;
+ int i;
+
+ if (!src || !len)
+ return NULL;
+
+ l = ascii85_encode_len(len);
+
+ /*
+ * Ascii85 outputs either a 5 byte string or a 1 byte string. So we
+ * account for the worst case of 5 bytes per dword plus the 1 for '\0'
+ */
+ buffer_size = (l * 5) + 1;
+
+ buf = kvmalloc(buffer_size, GFP_KERNEL);
+ if (!buf)
+ return NULL;
+
+ for (i = 0; i < l; i++)
+ buf_itr += snprintf(buf + buf_itr, buffer_size - buf_itr, "%s",
+ ascii85_encode(src[i], out));
+
+ return buf;
+}
+
+/*
+ * Convert the binary data in the gpu crash state capture(like bos and
+ * ringbuffer data) to ascii85 encoded strings. Note that the encoded
+ * string is NULL terminated.
+ */
+static void crashstate_worker(struct work_struct *work)
+{
+ struct msm_gpu_state *state;
+ struct msm_gpu *gpu = container_of(work, struct msm_gpu,
+ crashstate_work);
+ int i;
+
+ state = msm_gpu_crashstate_get(gpu);
+ if (!state)
+ return;
+
+ for (i = 0; i < MSM_GPU_MAX_RINGS; i++) {
+ void *buf = NULL;
+
+ if (!state->ring[i].data)
+ continue;
+
+ buf = state->ring[i].data;
+
+ state->ring[i].data = msm_gpu_ascii85_encode_buf(buf,
+ state->ring[i].data_size);
+ kvfree(buf);
+ }
+
+ for (i = 0; i < state->nr_bos; i++) {
+ u32 *buf = NULL;
+ long datalen, j;
+
+ if (!state->bos[i].data)
+ continue;
+
+ buf = state->bos[i].data;
+
+ /*
+ * Only dump the non-zero part of the buffer - rarely will
+ * any data completely fill the entire allocated size of the
+ * buffer
+ */
+ for (datalen = 0, j = 0; j < state->bos[i].size >> 2; j++)
+ if (buf[j])
+ datalen = ((j + 1) << 2);
+
+ state->bos[i].data = msm_gpu_ascii85_encode_buf(buf, datalen);
+ kvfree(buf);
+ }
+
+ msm_gpu_crashstate_put(gpu);
+
+ dev_coredumpm(gpu->dev->dev, THIS_MODULE, gpu, 0, GFP_KERNEL,
+ msm_gpu_devcoredump_read, msm_gpu_devcoredump_free);
+}
+
static void recover_worker(struct work_struct *work)
{
struct msm_gpu *gpu = container_of(work, struct msm_gpu, recover_work);
@@ -856,6 +942,7 @@ int msm_gpu_init(struct drm_device *drm, struct platform_device *pdev,
INIT_LIST_HEAD(&gpu->active_list);
INIT_WORK(&gpu->retire_work, retire_worker);
INIT_WORK(&gpu->recover_work, recover_worker);
+ INIT_WORK(&gpu->crashstate_work, crashstate_worker);
timer_setup(&gpu->hangcheck_timer, hangcheck_handler, 0);
diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
index f82bac0..8825069 100644
--- a/drivers/gpu/drm/msm/msm_gpu.h
+++ b/drivers/gpu/drm/msm/msm_gpu.h
@@ -137,6 +137,7 @@ struct msm_gpu {
} devfreq;
struct msm_gpu_state *crashstate;
+ struct work_struct crashstate_work;
};
/* It turns out that all targets use the same ringbuffer size */
--
1.9.1
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