Messages in this thread | | | Date | Thu, 3 May 2012 12:21:05 +0300 | From | Dan Carpenter <> | Subject | Re: [Patch 1/4] ipc/mqueue: improve performance of send/recv |
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On Tue, May 01, 2012 at 01:50:52PM -0400, Doug Ledford wrote: > @@ -150,16 +241,25 @@ static struct inode *mqueue_get_inode(struct super_block *sb, > info->attr.mq_maxmsg = attr->mq_maxmsg; > info->attr.mq_msgsize = attr->mq_msgsize; > } > - mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); > - if (mq_msg_tblsz > PAGE_SIZE) > - info->messages = vmalloc(mq_msg_tblsz); > - else > - info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); > - if (!info->messages) > - goto out_inode; > + /* > + * We used to allocate a static array of pointers and account > + * the size of that array as well as one msg_msg struct per > + * possible message into the queue size. That's no longer > + * accurate as the queue is now an rbtree and will grow and > + * shrink depending on usage patterns. We can, however, still > + * account one msg_msg struct per message, but the nodes are > + * allocated depending on priority usage, and most programs > + * only use one, or a handful, of priorities. However, since > + * this is pinned memory, we need to assume worst case, so > + * that means the min(mq_maxmsg, max_priorities) * struct > + * posix_msg_tree_node. > + */ > + mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) + > + min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) * > + sizeof(struct posix_msg_tree_node);
"info->attr.mq_maxmsg" is a long, but the min_t() truncates it to an unsigned int. I'm not familiar with this code so I don't know if that's a problem...
We do the same thing in mqueue_evict_inode() and mq_attr_ok().
regards, dan carpenter
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