From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3EDF4C71133 for ; Wed, 11 Jun 2025 15:29:20 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id D6B2710E6AB; Wed, 11 Jun 2025 15:29:19 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=igalia.com header.i=@igalia.com header.b="cHbbKNhr"; dkim-atps=neutral Received: from fanzine2.igalia.com (fanzine2.igalia.com [213.97.179.56]) by gabe.freedesktop.org (Postfix) with ESMTPS id 3C7A110E6A9; Wed, 11 Jun 2025 15:29:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From: References:Cc:To:Subject:MIME-Version:Date:Message-ID:Sender:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=0r5SdQ/0L/7BLhNXEpm/mv03XglIjWInycPNIZEV/90=; b=cHbbKNhrFvgV6lZV4yqX1KM5kA 1U+7WDR0aBf8vm9kUUr6EkKs3DqXzzQxXY8bzA3ckASSTj5ZMMznLasIIkA5j6+a5AKqqJQT70Kax THXNrNF0PbIG3POp3pn26rCdbiMoh9rVnn/+/t/mYBsf/rk8rsa4zQpR5RI/IWns2q0hKSbwfF5+w 57B87DiLHz2wIHpAKcy6d+AeV1hSEeL+rHeCrmA4LTGsJ4Gk2fevn0kr+jenX4jsA85M7wljYZ+zD i78BaWk2CkqPMhHbHm1l3fd1XHcLroMM/RKAZ+w8lPVVh7IlTy9smXZAUCThseKMcrqbh5DkmlFLC KJftCSXA==; Received: from [81.79.92.254] (helo=[192.168.0.101]) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_128_GCM:128) (Exim) id 1uPNO7-002Fxu-7b; Wed, 11 Jun 2025 17:29:15 +0200 Message-ID: <10e83252-e565-4cb4-9bc2-ae238528df92@igalia.com> Date: Wed, 11 Jun 2025 16:29:14 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 6/6] drm/syncobj: Add a fast path to drm_syncobj_array_find To: =?UTF-8?Q?Christian_K=C3=B6nig?= , dri-devel@lists.freedesktop.org Cc: kernel-dev@igalia.com, amd-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, =?UTF-8?Q?Michel_D=C3=A4nzer?= , =?UTF-8?Q?Ma=C3=ADra_Canal?= References: <20250611140057.27259-1-tvrtko.ursulin@igalia.com> <20250611140057.27259-7-tvrtko.ursulin@igalia.com> Content-Language: en-GB From: Tvrtko Ursulin In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" On 11/06/2025 15:21, Christian König wrote: > On 6/11/25 16:00, Tvrtko Ursulin wrote: >> Running the Cyberpunk 2077 benchmark we can observe that the lookup helper >> is relatively hot, but the 97% of the calls are for a single object. (~3% >> for two points, and never more than three points. While a more trivial >> workload like vkmark under Plasma is even more skewed to single point >> lookups.) >> >> Therefore lets add a fast path to bypass the kmalloc_array/kfree and use a >> pre-allocated stack array for those cases. > > Have you considered using memdup_user()? That's using a separate bucket IIRC and might give similar performance. I haven't but I can try it. I would be surprised if it made a (positive) difference though. And I realised I need to repeat the benchmarks anyway, since in v4 I had to stop doing access_ok+__get_user, after kernel test robot let me know 64-bit get_user is a not a thing on all platforms. I thought the gains are from avoiding allocations but, as you say, now I need to see if copy_from_user doesn't nullify them.. > If that is still not sufficient I'm really wondering if we shouldn't have a macro for doing this. It's a really common use case as far as I can see. Hmm macro for what exactly? Regards, Tvrtko >> Signed-off-by: Tvrtko Ursulin >> Reviewed-by: Maíra Canal >> --- >> v2: >> * Added comments describing how the fast path arrays were sized. >> * Make container freeing criteria clearer by using a boolean. >> --- >> drivers/gpu/drm/drm_syncobj.c | 56 +++++++++++++++++++++++++++-------- >> 1 file changed, 44 insertions(+), 12 deletions(-) >> >> diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c >> index be5905dca87f..65c301852f0d 100644 >> --- a/drivers/gpu/drm/drm_syncobj.c >> +++ b/drivers/gpu/drm/drm_syncobj.c >> @@ -1259,6 +1259,8 @@ EXPORT_SYMBOL(drm_timeout_abs_to_jiffies); >> static int drm_syncobj_array_find(struct drm_file *file_private, >> u32 __user *handles, >> uint32_t count, >> + struct drm_syncobj **stack_syncobjs, >> + u32 stack_count, >> struct drm_syncobj ***syncobjs_out) >> { >> struct drm_syncobj **syncobjs; >> @@ -1268,9 +1270,13 @@ static int drm_syncobj_array_find(struct drm_file *file_private, >> if (!access_ok(handles, count * sizeof(*handles))) >> return -EFAULT; >> >> - syncobjs = kmalloc_array(count, sizeof(*syncobjs), GFP_KERNEL); >> - if (!syncobjs) >> - return -ENOMEM; >> + if (count > stack_count) { >> + syncobjs = kmalloc_array(count, sizeof(*syncobjs), GFP_KERNEL); >> + if (!syncobjs) >> + return -ENOMEM; >> + } else { >> + syncobjs = stack_syncobjs; >> + } >> >> for (i = 0; i < count; i++) { >> u32 handle; >> @@ -1292,25 +1298,31 @@ static int drm_syncobj_array_find(struct drm_file *file_private, >> err_put_syncobjs: >> while (i-- > 0) >> drm_syncobj_put(syncobjs[i]); >> - kfree(syncobjs); >> + >> + if (syncobjs != stack_syncobjs) >> + kfree(syncobjs); >> >> return ret; >> } >> >> static void drm_syncobj_array_free(struct drm_syncobj **syncobjs, >> - uint32_t count) >> + uint32_t count, >> + bool free_container) >> { >> uint32_t i; >> >> for (i = 0; i < count; i++) >> drm_syncobj_put(syncobjs[i]); >> - kfree(syncobjs); >> + >> + if (free_container) >> + kfree(syncobjs); >> } >> >> int >> drm_syncobj_wait_ioctl(struct drm_device *dev, void *data, >> struct drm_file *file_private) >> { >> + struct drm_syncobj *stack_syncobjs[DRM_SYNCOBJ_FAST_PATH_ENTRIES]; >> struct drm_syncobj_wait *args = data; >> ktime_t deadline, *pdeadline = NULL; >> u32 count = args->count_handles; >> @@ -1336,6 +1348,8 @@ drm_syncobj_wait_ioctl(struct drm_device *dev, void *data, >> ret = drm_syncobj_array_find(file_private, >> u64_to_user_ptr(args->handles), >> count, >> + stack_syncobjs, >> + ARRAY_SIZE(stack_syncobjs), >> &syncobjs); >> if (ret < 0) >> return ret; >> @@ -1354,7 +1368,7 @@ drm_syncobj_wait_ioctl(struct drm_device *dev, void *data, >> &first, >> pdeadline); >> >> - drm_syncobj_array_free(syncobjs, count); >> + drm_syncobj_array_free(syncobjs, count, syncobjs != stack_syncobjs); >> >> if (timeout < 0) >> return timeout; >> @@ -1368,6 +1382,7 @@ int >> drm_syncobj_timeline_wait_ioctl(struct drm_device *dev, void *data, >> struct drm_file *file_private) >> { >> + struct drm_syncobj *stack_syncobjs[DRM_SYNCOBJ_FAST_PATH_ENTRIES]; >> struct drm_syncobj_timeline_wait *args = data; >> ktime_t deadline, *pdeadline = NULL; >> u32 count = args->count_handles; >> @@ -1394,6 +1409,8 @@ drm_syncobj_timeline_wait_ioctl(struct drm_device *dev, void *data, >> ret = drm_syncobj_array_find(file_private, >> u64_to_user_ptr(args->handles), >> count, >> + stack_syncobjs, >> + ARRAY_SIZE(stack_syncobjs), >> &syncobjs); >> if (ret < 0) >> return ret; >> @@ -1412,7 +1429,7 @@ drm_syncobj_timeline_wait_ioctl(struct drm_device *dev, void *data, >> &first, >> pdeadline); >> >> - drm_syncobj_array_free(syncobjs, count); >> + drm_syncobj_array_free(syncobjs, count, syncobjs != stack_syncobjs); >> >> if (timeout < 0) >> return timeout; >> @@ -1529,6 +1546,7 @@ int >> drm_syncobj_reset_ioctl(struct drm_device *dev, void *data, >> struct drm_file *file_private) >> { >> + struct drm_syncobj *stack_syncobjs[DRM_SYNCOBJ_FAST_PATH_ENTRIES]; >> struct drm_syncobj_array *args = data; >> struct drm_syncobj **syncobjs; >> uint32_t i; >> @@ -1546,6 +1564,8 @@ drm_syncobj_reset_ioctl(struct drm_device *dev, void *data, >> ret = drm_syncobj_array_find(file_private, >> u64_to_user_ptr(args->handles), >> args->count_handles, >> + stack_syncobjs, >> + ARRAY_SIZE(stack_syncobjs), >> &syncobjs); >> if (ret < 0) >> return ret; >> @@ -1553,7 +1573,8 @@ drm_syncobj_reset_ioctl(struct drm_device *dev, void *data, >> for (i = 0; i < args->count_handles; i++) >> drm_syncobj_replace_fence(syncobjs[i], NULL); >> >> - drm_syncobj_array_free(syncobjs, args->count_handles); >> + drm_syncobj_array_free(syncobjs, args->count_handles, >> + syncobjs != stack_syncobjs); >> >> return 0; >> } >> @@ -1562,6 +1583,7 @@ int >> drm_syncobj_signal_ioctl(struct drm_device *dev, void *data, >> struct drm_file *file_private) >> { >> + struct drm_syncobj *stack_syncobjs[DRM_SYNCOBJ_FAST_PATH_ENTRIES]; >> struct drm_syncobj_array *args = data; >> struct drm_syncobj **syncobjs; >> uint32_t i; >> @@ -1579,6 +1601,8 @@ drm_syncobj_signal_ioctl(struct drm_device *dev, void *data, >> ret = drm_syncobj_array_find(file_private, >> u64_to_user_ptr(args->handles), >> args->count_handles, >> + stack_syncobjs, >> + ARRAY_SIZE(stack_syncobjs), >> &syncobjs); >> if (ret < 0) >> return ret; >> @@ -1589,7 +1613,8 @@ drm_syncobj_signal_ioctl(struct drm_device *dev, void *data, >> break; >> } >> >> - drm_syncobj_array_free(syncobjs, args->count_handles); >> + drm_syncobj_array_free(syncobjs, args->count_handles, >> + syncobjs != stack_syncobjs); >> >> return ret; >> } >> @@ -1598,6 +1623,7 @@ int >> drm_syncobj_timeline_signal_ioctl(struct drm_device *dev, void *data, >> struct drm_file *file_private) >> { >> + struct drm_syncobj *stack_syncobjs[DRM_SYNCOBJ_FAST_PATH_ENTRIES]; >> struct drm_syncobj_timeline_array *args = data; >> uint64_t __user *points = u64_to_user_ptr(args->points); >> uint32_t i, j, count = args->count_handles; >> @@ -1617,6 +1643,8 @@ drm_syncobj_timeline_signal_ioctl(struct drm_device *dev, void *data, >> ret = drm_syncobj_array_find(file_private, >> u64_to_user_ptr(args->handles), >> count, >> + stack_syncobjs, >> + ARRAY_SIZE(stack_syncobjs), >> &syncobjs); >> if (ret < 0) >> return ret; >> @@ -1653,7 +1681,7 @@ drm_syncobj_timeline_signal_ioctl(struct drm_device *dev, void *data, >> err_chains: >> kfree(chains); >> out: >> - drm_syncobj_array_free(syncobjs, count); >> + drm_syncobj_array_free(syncobjs, count, syncobjs != stack_syncobjs); >> >> return ret; >> } >> @@ -1661,6 +1689,7 @@ drm_syncobj_timeline_signal_ioctl(struct drm_device *dev, void *data, >> int drm_syncobj_query_ioctl(struct drm_device *dev, void *data, >> struct drm_file *file_private) >> { >> + struct drm_syncobj *stack_syncobjs[DRM_SYNCOBJ_FAST_PATH_ENTRIES]; >> struct drm_syncobj_timeline_array *args = data; >> struct drm_syncobj **syncobjs; >> uint64_t __user *points = u64_to_user_ptr(args->points); >> @@ -1679,6 +1708,8 @@ int drm_syncobj_query_ioctl(struct drm_device *dev, void *data, >> ret = drm_syncobj_array_find(file_private, >> u64_to_user_ptr(args->handles), >> args->count_handles, >> + stack_syncobjs, >> + ARRAY_SIZE(stack_syncobjs), >> &syncobjs); >> if (ret < 0) >> return ret; >> @@ -1722,7 +1753,8 @@ int drm_syncobj_query_ioctl(struct drm_device *dev, void *data, >> if (ret) >> break; >> } >> - drm_syncobj_array_free(syncobjs, args->count_handles); >> + drm_syncobj_array_free(syncobjs, args->count_handles, >> + syncobjs != stack_syncobjs); >> >> return ret; >> } >