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<p class="msipheadera92e061b" style="margin:0in;margin-bottom:.0001pt"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#0078D7">[AMD Official Use Only - Internal Distribution Only]</span><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">-----Original Message-----<br>
From: Andrey Grodzovsky <andrey.grodzovsky@amd.com> <br>
Sent: Thursday, December 12, 2019 4:39 AM<br>
To: dri-devel@lists.freedesktop.org; amd-gfx@lists.freedesktop.org<br>
Cc: Deucher, Alexander <Alexander.Deucher@amd.com>; Ma, Le <Le.Ma@amd.com>; Zhang, Hawking <Hawking.Zhang@amd.com>; Quan, Evan <Evan.Quan@amd.com>; Grodzovsky, Andrey <Andrey.Grodzovsky@amd.com><br>
Subject: [RESEND PATCH 2/5] drm: Add Reusable task barrier.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">It is used to synchronize N threads at a rendevouz point before execution of critical code that has to be started by all the threads at approximatly the same time.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">Signed-off-by: Andrey Grodzovsky <<a href="mailto:andrey.grodzovsky@amd.com"><span style="color:windowtext;text-decoration:none">andrey.grodzovsky@amd.com</span></a>><o:p></o:p></p>
<p class="MsoPlainText">---<o:p></o:p></p>
<p class="MsoPlainText">include/drm/task_barrier.h | 106 +++++++++++++++++++++++++++++++++++++++++++++<o:p></o:p></p>
<p class="MsoPlainText">1 file changed, 106 insertions(+)<o:p></o:p></p>
<p class="MsoPlainText">create mode 100644 include/drm/task_barrier.h<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">diff --git a/include/drm/task_barrier.h b/include/drm/task_barrier.h new file mode 100644 index 0000000..81fb0f7<o:p></o:p></p>
<p class="MsoPlainText">--- /dev/null<o:p></o:p></p>
<p class="MsoPlainText">+++ b/include/drm/task_barrier.h<o:p></o:p></p>
<p class="MsoPlainText">@@ -0,0 +1,106 @@<o:p></o:p></p>
<p class="MsoPlainText">+/*<o:p></o:p></p>
<p class="MsoPlainText">+ * Copyright 2019 Advanced Micro Devices, Inc.<o:p></o:p></p>
<p class="MsoPlainText">+ *<o:p></o:p></p>
<p class="MsoPlainText">+ * Permission is hereby granted, free of charge, to any person
<o:p></o:p></p>
<p class="MsoPlainText">+obtaining a<o:p></o:p></p>
<p class="MsoPlainText">+ * copy of this software and associated documentation files (the
<o:p></o:p></p>
<p class="MsoPlainText">+"Software"),<o:p></o:p></p>
<p class="MsoPlainText">+ * to deal in the Software without restriction, including without
<o:p></o:p></p>
<p class="MsoPlainText">+limitation<o:p></o:p></p>
<p class="MsoPlainText">+ * the rights to use, copy, modify, merge, publish, distribute,
<o:p></o:p></p>
<p class="MsoPlainText">+sublicense,<o:p></o:p></p>
<p class="MsoPlainText">+ * and/or sell copies of the Software, and to permit persons to whom
<o:p></o:p></p>
<p class="MsoPlainText">+the<o:p></o:p></p>
<p class="MsoPlainText">+ * Software is furnished to do so, subject to the following conditions:<o:p></o:p></p>
<p class="MsoPlainText">+ *<o:p></o:p></p>
<p class="MsoPlainText">+ * The above copyright notice and this permission notice shall be
<o:p></o:p></p>
<p class="MsoPlainText">+included in<o:p></o:p></p>
<p class="MsoPlainText">+ * all copies or substantial portions of the Software.<o:p></o:p></p>
<p class="MsoPlainText">+ *<o:p></o:p></p>
<p class="MsoPlainText">+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
<o:p></o:p></p>
<p class="MsoPlainText">+EXPRESS OR<o:p></o:p></p>
<p class="MsoPlainText">+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
<o:p></o:p></p>
<p class="MsoPlainText">+MERCHANTABILITY,<o:p></o:p></p>
<p class="MsoPlainText">+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
<o:p></o:p></p>
<p class="MsoPlainText">+SHALL<o:p></o:p></p>
<p class="MsoPlainText">+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM,
<o:p></o:p></p>
<p class="MsoPlainText">+DAMAGES OR<o:p></o:p></p>
<p class="MsoPlainText">+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
<o:p></o:p></p>
<p class="MsoPlainText">+OTHERWISE,<o:p></o:p></p>
<p class="MsoPlainText">+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
<o:p></o:p></p>
<p class="MsoPlainText">+OR<o:p></o:p></p>
<p class="MsoPlainText">+ * OTHER DEALINGS IN THE SOFTWARE.<o:p></o:p></p>
<p class="MsoPlainText">+ *<o:p></o:p></p>
<p class="MsoPlainText">+ */<o:p></o:p></p>
<p class="MsoPlainText">+#include <linux/semaphore.h><o:p></o:p></p>
<p class="MsoPlainText">+#include <linux/atomic.h><o:p></o:p></p>
<p class="MsoPlainText">+<o:p></o:p></p>
<p class="MsoPlainText">+/*<o:p></o:p></p>
<p class="MsoPlainText">+ * Reusable 2 PHASE task barrier (randevouz point) implementation for N tasks.<o:p></o:p></p>
<p class="MsoPlainText">+ * Based on the Little book of sempahores - <o:p></o:p></p>
<p class="MsoPlainText">+https://greenteapress.com/wp/semaphores/<o:p></o:p></p>
<p class="MsoPlainText">+ */<o:p></o:p></p>
<p class="MsoPlainText">+<o:p></o:p></p>
<p class="MsoPlainText">+<o:p></o:p></p>
<p class="MsoPlainText">+<o:p></o:p></p>
<p class="MsoPlainText">+#ifndef DRM_TASK_BARRIER_H_<o:p></o:p></p>
<p class="MsoPlainText">+#define DRM_TASK_BARRIER_H_<o:p></o:p></p>
<p class="MsoPlainText">+<o:p></o:p></p>
<p class="MsoPlainText"><span style="color:black"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="color:#203864">[Le]: It might be better to prefix “drm_” to the functions and structure below, even this header file name.
<o:p></o:p></span></p>
<p class="MsoPlainText"><span style="color:black"><o:p> </o:p></span></p>
<p class="MsoPlainText">+/*<o:p></o:p></p>
<p class="MsoPlainText">+ * Represents an instance of a task barrier.<o:p></o:p></p>
<p class="MsoPlainText">+ */<o:p></o:p></p>
<p class="MsoPlainText">+struct task_barrier {<o:p></o:p></p>
<p class="MsoPlainText">+ unsigned int n;<o:p></o:p></p>
<p class="MsoPlainText"><span style="color:#203864">[Le]: We can define it as signed type here for more common use.<o:p></o:p></span></p>
<p class="MsoPlainText">+ atomic_t count;<o:p></o:p></p>
<p class="MsoPlainText">+ struct semaphore enter_turnstile;<o:p></o:p></p>
<p class="MsoPlainText">+ struct semaphore exit_turnstile;<o:p></o:p></p>
<p class="MsoPlainText">+};<o:p></o:p></p>
<p class="MsoPlainText">+<o:p></o:p></p>
<p class="MsoPlainText">+static inline void task_barrier_signal_turnstile(struct semaphore *turnstile,<o:p></o:p></p>
<p class="MsoPlainText">+ unsigned int n)<o:p></o:p></p>
<p class="MsoPlainText">+{<o:p></o:p></p>
<p class="MsoPlainText">+ int i;<o:p></o:p></p>
<p class="MsoPlainText">+<o:p></o:p></p>
<p class="MsoPlainText">+ for (i = 0 ; i < n; i++)<o:p></o:p></p>
<p class="MsoPlainText">+ up(turnstile);<o:p></o:p></p>
<p class="MsoPlainText">+}<o:p></o:p></p>
<p class="MsoPlainText">+<o:p></o:p></p>
<p class="MsoPlainText">+static inline void task_barrier_init(struct task_barrier *tb) {<o:p></o:p></p>
<p class="MsoPlainText">+ tb->n = 0;<o:p></o:p></p>
<p class="MsoPlainText">+ atomic_set(&tb->count, 0);<o:p></o:p></p>
<p class="MsoPlainText">+ sema_init(&tb->enter_turnstile, 0);<o:p></o:p></p>
<p class="MsoPlainText">+ sema_init(&tb->exit_turnstile, 0);<o:p></o:p></p>
<p class="MsoPlainText">+}<o:p></o:p></p>
<p class="MsoPlainText">+<o:p></o:p></p>
<p class="MsoPlainText">+static inline void task_barrier_add_task(struct task_barrier *tb) {<o:p></o:p></p>
<p class="MsoPlainText">+ tb->n++;<o:p></o:p></p>
<p class="MsoPlainText">+}<o:p></o:p></p>
<p class="MsoPlainText">+<o:p></o:p></p>
<p class="MsoPlainText">+static inline void task_barrier_rem_task(struct task_barrier *tb) {<o:p></o:p></p>
<p class="MsoPlainText">+ tb->n--;<o:p></o:p></p>
<p class="MsoPlainText">+}<o:p></o:p></p>
<p class="MsoPlainText">+<o:p></o:p></p>
<p class="MsoPlainText">+/*<o:p></o:p></p>
<p class="MsoPlainText">+ * Lines up all the threads BEFORE the critical point.<o:p></o:p></p>
<p class="MsoPlainText">+ *<o:p></o:p></p>
<p class="MsoPlainText">+ * When all thread passed this code the entry barrier is back to locked state.<o:p></o:p></p>
<p class="MsoPlainText">+ */<o:p></o:p></p>
<p class="MsoPlainText">+static inline void task_barrier_enter(struct task_barrier *tb) {<o:p></o:p></p>
<p class="MsoPlainText">+ if (atomic_inc_return(&tb->count) == tb->n)<o:p></o:p></p>
<p class="MsoPlainText">+ task_barrier_signal_turnstile(&tb->enter_turnstile, tb->n);<o:p></o:p></p>
<p class="MsoPlainText">+<o:p></o:p></p>
<p class="MsoPlainText">+ down(&tb->enter_turnstile);<o:p></o:p></p>
<p class="MsoPlainText">+}<o:p></o:p></p>
<p class="MsoPlainText">+<o:p></o:p></p>
<p class="MsoPlainText">+/*<o:p></o:p></p>
<p class="MsoPlainText">+ * Lines up all the threads AFTER the critical point.<o:p></o:p></p>
<p class="MsoPlainText">+ *<o:p></o:p></p>
<p class="MsoPlainText">+ * This function is used to avoid any one thread running ahead of the
<o:p></o:p></p>
<p class="MsoPlainText">+reset if<o:p></o:p></p>
<p class="MsoPlainText"><span style="color:#203864">[Le]: No need to mention “reset” here.<o:p></o:p></span></p>
<p class="MsoPlainText"><span style="color:#203864"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="color:#203864">With the above addressed, Acked-by: Le Ma
<a href="mailto:Le.Ma@amd.com"><span style="color:#033160">Le.Ma@amd.com</span></a><o:p></o:p></span></p>
<p class="MsoPlainText"><span style="color:#203864"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="color:#203864">Regards,<o:p></o:p></span></p>
<p class="MsoPlainText"><span style="color:#203864">Ma Le<o:p></o:p></span></p>
<p class="MsoPlainText">+ * the barrier is used in a loop (repeatedly) .<o:p></o:p></p>
<p class="MsoPlainText">+ */<o:p></o:p></p>
<p class="MsoPlainText">+static inline void task_barrier_exit(struct task_barrier *tb) {<o:p></o:p></p>
<p class="MsoPlainText">+ if (atomic_dec_return(&tb->count) == 0)<o:p></o:p></p>
<p class="MsoPlainText">+ task_barrier_signal_turnstile(&tb->exit_turnstile, tb->n);<o:p></o:p></p>
<p class="MsoPlainText">+<o:p></o:p></p>
<p class="MsoPlainText">+ down(&tb->exit_turnstile);<o:p></o:p></p>
<p class="MsoPlainText">+}<o:p></o:p></p>
<p class="MsoPlainText">+<o:p></o:p></p>
<p class="MsoPlainText">+static inline void task_barrier_full(struct task_barrier *tb) {<o:p></o:p></p>
<p class="MsoPlainText">+ task_barrier_enter(tb);<o:p></o:p></p>
<p class="MsoPlainText">+ task_barrier_exit(tb);<o:p></o:p></p>
<p class="MsoPlainText">+}<o:p></o:p></p>
<p class="MsoPlainText">+<o:p></o:p></p>
<p class="MsoPlainText">+#endif<o:p></o:p></p>
<p class="MsoPlainText">--<o:p></o:p></p>
<p class="MsoPlainText">2.7.4<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
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