Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755952Ab0LPC67 (ORCPT ); Wed, 15 Dec 2010 21:58:59 -0500 Received: from hera.kernel.org ([140.211.167.34]:52700 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755148Ab0LPC65 (ORCPT ); Wed, 15 Dec 2010 21:58:57 -0500 Date: Thu, 16 Dec 2010 02:58:41 GMT From: tip-bot for Andres Salomon Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, dilinger@queued.net, tglx@linutronix.de, hpa@linux.intel.com Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, dilinger@queued.net, tglx@linutronix.de, hpa@linux.intel.com In-Reply-To: <20101129153951.74202a84@queued.net> References: <20101129153951.74202a84@queued.net> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/olpc] x86, olpc: Speed up device tree creation during boot Message-ID: Git-Commit-ID: b5318d302f8a20eacbbfc01b0ee35b108085a363 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Thu, 16 Dec 2010 02:58:41 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2803 Lines: 79 Commit-ID: b5318d302f8a20eacbbfc01b0ee35b108085a363 Gitweb: http://git.kernel.org/tip/b5318d302f8a20eacbbfc01b0ee35b108085a363 Author: Andres Salomon AuthorDate: Mon, 29 Nov 2010 23:39:51 +0000 Committer: H. Peter Anvin CommitDate: Wed, 15 Dec 2010 17:11:40 -0800 x86, olpc: Speed up device tree creation during boot Calling alloc_bootmem() for tiny chunks of memory over and over is really slow; on an XO-1, it caused the time between when the kernel started booting and when the display came alive (post-lxfb probe) to increase to 44s. This patch optimizes the prom_early_alloc function by calling alloc_bootmem for 4k-sized blocks of memory, and handing out chunks of that to callers. With this patch, the time between kernel load and display initialization decreased to 23s. If there's a better way to do this early in the boot process, please let me know. (Note: increasing the chunk size to 16k didn't noticably affect boot time, and wasted 9k.) v4: clarify comment, requested by hpa v3: fix wasted memory buglet found by Milton Miller, and style fix. v2: reorder prom_early_alloc as suggested by Grant. Signed-off-by: Andres Salomon LKML-Reference: <20101129153951.74202a84@queued.net> Signed-off-by: H. Peter Anvin --- arch/x86/platform/olpc/olpc_dt.c | 28 +++++++++++++++++++++++----- 1 files changed, 23 insertions(+), 5 deletions(-) diff --git a/arch/x86/platform/olpc/olpc_dt.c b/arch/x86/platform/olpc/olpc_dt.c index 7054697..dab8746 100644 --- a/arch/x86/platform/olpc/olpc_dt.c +++ b/arch/x86/platform/olpc/olpc_dt.c @@ -126,14 +126,32 @@ static unsigned int prom_early_allocated __initdata; void * __init prom_early_alloc(unsigned long size) { + static u8 *mem; + static size_t free_mem; void *res; - res = alloc_bootmem(size); - if (res) - memset(res, 0, size); - - prom_early_allocated += size; + if (free_mem < size) { + const size_t chunk_size = max(PAGE_SIZE, size); + + /* + * To mimimize the number of allocations, grab at least + * PAGE_SIZE of memory (that's an arbitrary choice that's + * fast enough on the platforms we care about while minimizing + * wasted bootmem) and hand off chunks of it to callers. + */ + res = alloc_bootmem(chunk_size); + if (!res) + return NULL; + prom_early_allocated += chunk_size; + memset(res, 0, chunk_size); + free_mem = chunk_size; + mem = res; + } + /* allocate from the local cache */ + free_mem -= size; + res = mem; + mem += size; return res; } -- 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/