Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932068AbXAOWjn (ORCPT ); Mon, 15 Jan 2007 17:39:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751519AbXAOWjn (ORCPT ); Mon, 15 Jan 2007 17:39:43 -0500 Received: from e4.ny.us.ibm.com ([32.97.182.144]:46590 "EHLO e4.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751516AbXAOWjm (ORCPT ); Mon, 15 Jan 2007 17:39:42 -0500 Message-ID: <45AC02A4.8080301@us.ibm.com> Date: Mon, 15 Jan 2007 16:39:32 -0600 From: Maynard Johnson Reply-To: maynardj@us.ibm.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.3) Gecko/20040910 X-Accept-Language: en-us, en MIME-Version: 1.0 To: michael@ellerman.id.au CC: cbe-oss-dev@ozlabs.org, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Arnd Bergmann Subject: Re: [PATCH] Cell SPU task notification -- updated patch: #1 References: <45A805A0.2080000@us.ibm.com> <1168826871.4622.32.camel@concordia.ozlabs.ibm.com> In-Reply-To: <1168826871.4622.32.camel@concordia.ozlabs.ibm.com> Content-Type: multipart/mixed; boundary="------------060808080906030204090802" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5499 Lines: 164 This is a multi-part message in MIME format. --------------060808080906030204090802 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Attached is an updated patch that addresses Michael Ellerman's comments. One comment made by Michael has not yet been addressed: The comment was in regard to the for-loop in spufs/sched.c:notify_spus_active(). He wondered if the scheduler can swap a context from one node to another. If so, there's a small window in this loop (where we switch the lock from one node's active list to the next) where it may be possible we might miss waking up a context and send a spurious wakeup to another. Arnd . . . can you comment on this question? Thanks. -Maynard --------------060808080906030204090802 Content-Type: text/x-diff; name="spu-notifier.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="spu-notifier.patch" Subject: Enable SPU switch notification to detect currently active SPU tasks. From: Maynard Johnson This patch adds to the capability of spu_switch_event_register so that the caller is also notified of currently active SPU tasks. It also exports spu_switch_event_register and spu_switch_event_unregister. Signed-off-by: Maynard Johnson Index: linux-2.6.19-rc6-arnd1+patches/arch/powerpc/platforms/cell/spufs/sched.c =================================================================== --- linux-2.6.19-rc6-arnd1+patches.orig/arch/powerpc/platforms/cell/spufs/sched.c 2006-12-04 10:56:04.730698720 -0600 +++ linux-2.6.19-rc6-arnd1+patches/arch/powerpc/platforms/cell/spufs/sched.c 2007-01-15 16:22:31.808461448 -0600 @@ -84,15 +84,42 @@ ctx ? ctx->object_id : 0, spu); } +static void notify_spus_active(void) +{ + int node; + /* Wake up the active spu_contexts. When the awakened processes + * sees their notify_active flag is set, they will call + * spu_notify_already_active(). + */ + for (node = 0; node < MAX_NUMNODES; node++) { + struct spu *spu; + mutex_lock(&spu_prio->active_mutex[node]); + list_for_each_entry(spu, &spu_prio->active_list[node], list) { + struct spu_context *ctx = spu->ctx; + spu->notify_active = 1; + wake_up_all(&ctx->stop_wq); + smp_wmb(); + } + mutex_unlock(&spu_prio->active_mutex[node]); + } + yield(); +} + int spu_switch_event_register(struct notifier_block * n) { - return blocking_notifier_chain_register(&spu_switch_notifier, n); + int ret; + ret = blocking_notifier_chain_register(&spu_switch_notifier, n); + if (!ret) + notify_spus_active(); + return ret; } +EXPORT_SYMBOL_GPL(spu_switch_event_register); int spu_switch_event_unregister(struct notifier_block * n) { return blocking_notifier_chain_unregister(&spu_switch_notifier, n); } +EXPORT_SYMBOL_GPL(spu_switch_event_unregister); static inline void bind_context(struct spu *spu, struct spu_context *ctx) @@ -250,6 +277,14 @@ return spu_get_idle(ctx, flags); } +void spu_notify_already_active(struct spu_context *ctx) +{ + struct spu *spu = ctx->spu; + if (!spu) + return; + spu_switch_notify(spu, ctx); +} + /* The three externally callable interfaces * for the scheduler begin here. * Index: linux-2.6.19-rc6-arnd1+patches/arch/powerpc/platforms/cell/spufs/spufs.h =================================================================== --- linux-2.6.19-rc6-arnd1+patches.orig/arch/powerpc/platforms/cell/spufs/spufs.h 2007-01-08 18:18:40.093354608 -0600 +++ linux-2.6.19-rc6-arnd1+patches/arch/powerpc/platforms/cell/spufs/spufs.h 2007-01-08 18:31:03.610345792 -0600 @@ -183,6 +183,7 @@ void spu_yield(struct spu_context *ctx); int __init spu_sched_init(void); void __exit spu_sched_exit(void); +void spu_notify_already_active(struct spu_context *ctx); extern char *isolated_loader; Index: linux-2.6.19-rc6-arnd1+patches/arch/powerpc/platforms/cell/spufs/run.c =================================================================== --- linux-2.6.19-rc6-arnd1+patches.orig/arch/powerpc/platforms/cell/spufs/run.c 2007-01-08 18:33:51.979311680 -0600 +++ linux-2.6.19-rc6-arnd1+patches/arch/powerpc/platforms/cell/spufs/run.c 2007-01-15 16:31:30.104499992 -0600 @@ -45,9 +45,11 @@ u64 pte_fault; *stat = ctx->ops->status_read(ctx); - if (ctx->state != SPU_STATE_RUNNABLE) - return 1; + smp_rmb(); + spu = ctx->spu; + if (ctx->state != SPU_STATE_RUNNABLE || spu->notify_active) + return 1; pte_fault = spu->dsisr & (MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED); return (!(*stat & 0x1) || pte_fault || spu->class_0_pending) ? 1 : 0; @@ -304,6 +306,7 @@ u32 *npc, u32 *event) { int ret; + struct * spu; u32 status; if (down_interruptible(&ctx->run_sema)) @@ -317,8 +320,16 @@ do { ret = spufs_wait(ctx->stop_wq, spu_stopped(ctx, &status)); + spu = ctx->spu; if (unlikely(ret)) break; + if (unlikely(spu->notify_active)) { + spu->notify_active = 0; + if (!(status & SPU_STATUS_STOPPED_BY_STOP)) { + spu_notify_already_active(ctx); + continue; + } + } if ((status & SPU_STATUS_STOPPED_BY_STOP) && (status >> SPU_STOP_STATUS_SHIFT == 0x2104)) { ret = spu_process_callback(ctx); --------------060808080906030204090802-- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/