Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751530AbbFMThi (ORCPT ); Sat, 13 Jun 2015 15:37:38 -0400 Received: from mail-wi0-f174.google.com ([209.85.212.174]:37740 "EHLO mail-wi0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751135AbbFMThe (ORCPT ); Sat, 13 Jun 2015 15:37:34 -0400 Date: Sat, 13 Jun 2015 21:40:39 +0200 From: Marcus Gelderie To: linux-kernel@vger.kernel.org Cc: mtk.manpages@gmail.com, dhowells@redhat.com, viro@zeniv.linux.org.uk, dledford@redhat.com Subject: [PATCH] ipc: Modify message queue accounting to reflect both total user data and auxiliary kernel data Message-ID: <20150613194039.GB31082@ramsey.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline User-Agent: Mutt/1.5.23+89 (0255b37be491) (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3768 Lines: 105 A while back, the message queue implementation in the kernel was improved to use btrees to speed up retrieval of messages (commit d6629859b36). The patch introducing the improved kernel handling of message queues has, as a by-product, changed the meaning of the QSIZE field in the pseudo-file created for the queue. Before, this field reflected the size of the user-data in the queue. Since, it now also takes kernel data structures into account, this is no no longer true. For example, if 13 bytes of user data are in the queue, on my machine the file reports a size of 61 bytes. There was some discussion on this topic before (for example https://lkml.org/lkml/2014/10/1/115). Reporting the size of the message queue in kernel has its merits, but doing so in the QSIZE field of the pseudo file corresponding to the queue is a breaking change. This patch therefore returns the QSIZE field to its original meaning. At the same time, it introduces a new field QKERSIZE that reflects the size of the queue in kernel (user data + kernel data). If the accounting should be improved, I'd be happy to take a look at that, too. I would propose to do that in terms of the newly introduced field. Signed-off-by: Marcus Gelderie --- ipc/mqueue.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/ipc/mqueue.c b/ipc/mqueue.c index 3aaea7f..7d4c464 100644 --- a/ipc/mqueue.c +++ b/ipc/mqueue.c @@ -41,7 +41,7 @@ #define MQUEUE_MAGIC 0x19800202 #define DIRENT_SIZE 20 -#define FILENT_SIZE 80 +#define FILENT_SIZE 90 #define SEND 0 #define RECV 1 @@ -82,8 +82,12 @@ struct mqueue_inode_info { /* for tasks waiting for free space and messages, respectively */ struct ext_wait_queue e_wait_q[2]; - unsigned long qsize; /* size of queue in memory (sum of all msgs) */ -}; + /* size of queue in memory (sum of all msgs plus kernel + * data structures) */ + unsigned long qsize; + + /* size of user data in the queue (sum of all msgs) */ + unsigned long q_usersize; }; static const struct inode_operations mqueue_dir_inode_operations; static const struct file_operations mqueue_file_operations; @@ -151,6 +155,7 @@ static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info) insert_msg: info->attr.mq_curmsgs++; info->qsize += msg->m_ts; + info->q_usersize += msg->m_ts; list_add_tail(&msg->m_list, &leaf->msg_list); return 0; } @@ -210,6 +215,7 @@ try_again: } info->attr.mq_curmsgs--; info->qsize -= msg->m_ts; + info->q_usersize -= msg->m_ts; return msg; } @@ -246,6 +252,7 @@ static struct inode *mqueue_get_inode(struct super_block *sb, info->notify_owner = NULL; info->notify_user_ns = NULL; info->qsize = 0; + info->q_usersize = 0; info->user = NULL; /* set when all is ok */ info->msg_tree = RB_ROOT; info->node_cache = NULL; @@ -491,13 +498,14 @@ static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, spin_lock(&info->lock); snprintf(buffer, sizeof(buffer), - "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", - info->qsize, + "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d QKERSIZE:%-10lu\n", + info->q_usersize, info->notify_owner ? info->notify.sigev_notify : 0, (info->notify_owner && info->notify.sigev_notify == SIGEV_SIGNAL) ? info->notify.sigev_signo : 0, - pid_vnr(info->notify_owner)); + pid_vnr(info->notify_owner), + info->qsize); spin_unlock(&info->lock); buffer[sizeof(buffer)-1] = '\0'; -- 2.4.3 -- 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/