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 X-Spam-Level: X-Spam-Status: No, score=-8.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8B093C04EB8 for ; Thu, 6 Dec 2018 16:12:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 426D320700 for ; Thu, 6 Dec 2018 16:12:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="Uly1QzyG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 426D320700 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=oracle.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726105AbeLFQMX (ORCPT ); Thu, 6 Dec 2018 11:12:23 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:51216 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725930AbeLFQMW (ORCPT ); Thu, 6 Dec 2018 11:12:22 -0500 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id wB6GAAIK088066; Thu, 6 Dec 2018 16:12:12 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=JKpDRoF13vRK0kRuu1xAPyd1lI2nDNemsInl5pztJRs=; b=Uly1QzyGOHuZhkaV/ZNgeftJdaTWwfoCqvHk6WyBoTg7nYUqTm1oCGXnbz6uRdR0s5EQ 9NBRndTLSd7WiyrhMYrOdiiN/dNU6uGT4koaQUOf8+0VydoToyHjR3mMQfE1ikWufGAP 8D/2Bta/DNghwED1YSie0PRdrcZG7wx4DkwqfrRmLv3r60cHR0uwj7HHapu7/Y0nwM02 nKrpq96gafOeYv0SO9hPRtEx6Z3mWFNmYA13hxmjRJNI0fNfV+7i18yOMZtJGERmLkfo StOe6GkAIQLzXM6wQD5b+tNlOU9/jVHmNeqvQE0e57J45Zk/9HJLJVx2smXgV78lKgqi BQ== Received: from userv0022.oracle.com (userv0022.oracle.com [156.151.31.74]) by userp2120.oracle.com with ESMTP id 2p3jxrs35n-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 06 Dec 2018 16:12:12 +0000 Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userv0022.oracle.com (8.14.4/8.14.4) with ESMTP id wB6GC6CG022492 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 6 Dec 2018 16:12:06 GMT Received: from abhmp0009.oracle.com (abhmp0009.oracle.com [141.146.116.15]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id wB6GC5w1014292; Thu, 6 Dec 2018 16:12:05 GMT Received: from [10.211.46.123] (/10.211.46.123) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 06 Dec 2018 08:12:05 -0800 Subject: Re: [PATCH RFC 1/1] swiotlb: add debugfs to track swiotlb buffer usage To: Dongli Zhang , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Cc: konrad.wilk@oracle.com, hch@lst.de, m.szyprowski@samsung.com, robin.murphy@arm.com References: <1544068785-20399-1-git-send-email-dongli.zhang@oracle.com> From: Joe Jin Message-ID: Date: Thu, 6 Dec 2018 08:12:02 -0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <1544068785-20399-1-git-send-email-dongli.zhang@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9098 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=2 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1812060138 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Dongli, Maybe move d_swiotlb_usage declare into swiotlb_create_debugfs(): void swiotlb_create_debugfs(void) { #ifdef CONFIG_DEBUG_FS static struct dentry *d_swiotlb_usage = NULL; if (d_swiotlb_usage) return; d_swiotlb_usage = debugfs_create_dir("swiotlb", NULL); if (!d_swiotlb_usage) return; debugfs_create_file("usage", 0600, d_swiotlb_usage, NULL, &swiotlb_usage_fops); #endif } And for io_tlb_used, possible add a check at the begin of swiotlb_tbl_map_single(), if there were not any free slots or not enough slots, return fail directly? Thanks, Joe On 12/5/18 7:59 PM, Dongli Zhang wrote: > The device driver will not be able to do dma operations once swiotlb buffer > is full, either because the driver is using so many IO TLB blocks inflight, > or because there is memory leak issue in device driver. To export the > swiotlb buffer usage via debugfs would help the user estimate the size of > swiotlb buffer to pre-allocate or analyze device driver memory leak issue. > > As the swiotlb can be initialized at very early stage when debugfs cannot > register successfully, this patch creates the debugfs entry on demand. > > Signed-off-by: Dongli Zhang > --- > kernel/dma/swiotlb.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 57 insertions(+) > > diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c > index 045930e..d3c8aa4 100644 > --- a/kernel/dma/swiotlb.c > +++ b/kernel/dma/swiotlb.c > @@ -35,6 +35,9 @@ > #include > #include > #include > +#ifdef CONFIG_DEBUG_FS > +#include > +#endif > > #include > #include > @@ -73,6 +76,13 @@ static phys_addr_t io_tlb_start, io_tlb_end; > */ > static unsigned long io_tlb_nslabs; > > +#ifdef CONFIG_DEBUG_FS > +/* > + * The number of used IO TLB block > + */ > +static unsigned long io_tlb_used; > +#endif > + > /* > * This is a free list describing the number of free entries available from > * each index > @@ -100,6 +110,41 @@ static DEFINE_SPINLOCK(io_tlb_lock); > > static int late_alloc; > > +#ifdef CONFIG_DEBUG_FS > + > +static struct dentry *d_swiotlb_usage; > + > +static int swiotlb_usage_show(struct seq_file *m, void *v) > +{ > + seq_printf(m, "%lu\n%lu\n", io_tlb_used, io_tlb_nslabs); > + return 0; > +} > + > +static int swiotlb_usage_open(struct inode *inode, struct file *filp) > +{ > + return single_open(filp, swiotlb_usage_show, NULL); > +} > + > +static const struct file_operations swiotlb_usage_fops = { > + .open = swiotlb_usage_open, > + .read = seq_read, > + .llseek = seq_lseek, > + .release = single_release, > +}; > + > +void swiotlb_create_debugfs(void) > +{ > + d_swiotlb_usage = debugfs_create_dir("swiotlb", NULL); > + > + if (!d_swiotlb_usage) > + return; > + > + debugfs_create_file("usage", 0600, d_swiotlb_usage, > + NULL, &swiotlb_usage_fops); > +} > + > +#endif > + > static int __init > setup_io_tlb_npages(char *str) > { > @@ -449,6 +494,11 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, > pr_warn_once("%s is active and system is using DMA bounce buffers\n", > sme_active() ? "SME" : "SEV"); > > +#ifdef CONFIG_DEBUG_FS > + if (unlikely(!d_swiotlb_usage)) > + swiotlb_create_debugfs(); > +#endif > + > mask = dma_get_seg_boundary(hwdev); > > tbl_dma_addr &= mask; > @@ -528,6 +578,9 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, > dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes)\n", size); > return SWIOTLB_MAP_ERROR; > found: > +#ifdef CONFIG_DEBUG_FS > + io_tlb_used += nslots; > +#endif > spin_unlock_irqrestore(&io_tlb_lock, flags); > > /* > @@ -588,6 +641,10 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr, > */ > for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--) > io_tlb_list[i] = ++count; > + > +#ifdef CONFIG_DEBUG_FS > + io_tlb_used -= nslots; > +#endif > } > spin_unlock_irqrestore(&io_tlb_lock, flags); > } >