From patchwork Tue Oct 29 06:54:15 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: liqiang X-Patchwork-Id: 13854410 X-Patchwork-Delegate: kuba@kernel.org Received: from szxga05-in.huawei.com (szxga05-in.huawei.com [45.249.212.191]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 535DF28E7; Tue, 29 Oct 2024 06:54:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.191 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730184864; cv=none; b=rBYjmd1TON7BfJDqNk05POkT2KqEzpl0dkI7xfztunNbcs+NTo5EMbLmQzUgHNPdzpDT9iMAlQGuB3fmlXomF1ZJ8HEwTdF92c86hW36VJUjnP5b9SWOChyPXZoPoNmXfZqaCpc51YOgUSpv7pnR9k/Xb8dTKGqaTG5KVN7g6i4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730184864; c=relaxed/simple; bh=ac7i+WSWlNHFVbuWBcf7pw+gZj8RycgBGSILsV7Dq2s=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=U9DPJAdE517y+LB86AJjPqq1T8ZKQPDWXZFX8jaP43Y7KBwYTpzcn6OeakHRJI0GSJs5wUal0kKjA5q5TBNtHTM9t7AkmvmKMEBRgHQ5wrJJRrvIZFr3ShY+7lMCC7oK82iofcwO4aLDDF3tq8ZmLj+SXsDwFm9KgROoku8y4Mk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.191 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.234]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4Xd18b18yVz1HLll; Tue, 29 Oct 2024 14:49:51 +0800 (CST) Received: from kwepemf200001.china.huawei.com (unknown [7.202.181.227]) by mail.maildlp.com (Postfix) with ESMTPS id 683B714037D; Tue, 29 Oct 2024 14:54:18 +0800 (CST) Received: from huawei.com (10.110.54.32) by kwepemf200001.china.huawei.com (7.202.181.227) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Tue, 29 Oct 2024 14:54:17 +0800 From: liqiang To: , , , , CC: , , , , , , Subject: [PATCH] net/smc: Optimize the search method of reused buf_desc Date: Tue, 29 Oct 2024 14:54:15 +0800 Message-ID: <20241029065415.1070-1-liqiang64@huawei.com> X-Mailer: git-send-email 2.23.0.windows.1 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To kwepemf200001.china.huawei.com (7.202.181.227) X-Patchwork-Delegate: kuba@kernel.org We create a lock-less link list for the currently idle reusable smc_buf_desc. When the 'used' filed mark to 0, it is added to the lock-less linked list. When a new connection is established, a suitable element is obtained directly, which eliminates the need for traversal and search, and does not require locking resource. A lock-free linked list is a linked list that uses atomic operations to optimize the producer-consumer model. Signed-off-by: liqiang --- net/smc/smc_core.c | 46 ++++++++++++++++++++++++++++------------------ net/smc/smc_core.h | 4 ++++ 2 files changed, 32 insertions(+), 18 deletions(-) diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c index 3b95828d9976..ac120f62313b 100644 --- a/net/smc/smc_core.c +++ b/net/smc/smc_core.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include #include @@ -872,6 +873,8 @@ static int smc_lgr_create(struct smc_sock *smc, struct smc_init_info *ini) for (i = 0; i < SMC_RMBE_SIZES; i++) { INIT_LIST_HEAD(&lgr->sndbufs[i]); INIT_LIST_HEAD(&lgr->rmbs[i]); + init_llist_head(&lgr->rmbs_free[i]); + init_llist_head(&lgr->sndbufs_free[i]); } lgr->next_link_id = 0; smc_lgr_list.num += SMC_LGR_NUM_INCR; @@ -1146,6 +1149,10 @@ static void smcr_buf_unuse(struct smc_buf_desc *buf_desc, bool is_rmb, /* memzero_explicit provides potential memory barrier semantics */ memzero_explicit(buf_desc->cpu_addr, buf_desc->len); WRITE_ONCE(buf_desc->used, 0); + if (is_rmb) + llist_add(&buf_desc->llist, &lgr->rmbs_free[buf_desc->bufsiz_comp]); + else + llist_add(&buf_desc->llist, &lgr->sndbufs_free[buf_desc->bufsiz_comp]); } } @@ -1172,6 +1179,8 @@ static void smc_buf_unuse(struct smc_connection *conn, } else { memzero_explicit(conn->sndbuf_desc->cpu_addr, conn->sndbuf_desc->len); WRITE_ONCE(conn->sndbuf_desc->used, 0); + llist_add(&conn->sndbuf_desc->llist, + &lgr->sndbufs_free[conn->sndbuf_desc->bufsiz_comp]); } } if (conn->rmb_desc) { @@ -1181,6 +1190,8 @@ static void smc_buf_unuse(struct smc_connection *conn, memzero_explicit(conn->rmb_desc->cpu_addr, conn->rmb_desc->len + sizeof(struct smcd_cdc_msg)); WRITE_ONCE(conn->rmb_desc->used, 0); + llist_add(&conn->rmb_desc->llist, + &lgr->rmbs_free[conn->rmb_desc->bufsiz_comp]); } } } @@ -2042,24 +2053,19 @@ int smc_uncompress_bufsize(u8 compressed) return (int)size; } -/* try to reuse a sndbuf or rmb description slot for a certain - * buffer size; if not available, return NULL - */ -static struct smc_buf_desc *smc_buf_get_slot(int compressed_bufsize, - struct rw_semaphore *lock, - struct list_head *buf_list) +/* use lock less list to save and find reuse buf desc */ +static struct smc_buf_desc *smc_buf_get_slot_free(struct llist_head *buf_llist) { - struct smc_buf_desc *buf_slot; + struct smc_buf_desc *buf_free; + struct llist_node *llnode; - down_read(lock); - list_for_each_entry(buf_slot, buf_list, list) { - if (cmpxchg(&buf_slot->used, 0, 1) == 0) { - up_read(lock); - return buf_slot; - } - } - up_read(lock); - return NULL; + if (llist_empty(buf_llist)) + return NULL; + // lock-less link list don't need an lock + llnode = llist_del_first(buf_llist); + buf_free = llist_entry(llnode, struct smc_buf_desc, llist); + WRITE_ONCE(buf_free->used, 1); + return buf_free; } /* one of the conditions for announcing a receiver's current window size is @@ -2364,6 +2370,7 @@ static int __smc_buf_create(struct smc_sock *smc, bool is_smcd, bool is_rmb) struct smc_connection *conn = &smc->conn; struct smc_link_group *lgr = conn->lgr; struct list_head *buf_list; + struct llist_head *buf_llist; int bufsize, bufsize_comp; struct rw_semaphore *lock; /* lock buffer list */ bool is_dgraded = false; @@ -2379,15 +2386,17 @@ static int __smc_buf_create(struct smc_sock *smc, bool is_smcd, bool is_rmb) bufsize_comp >= 0; bufsize_comp--) { if (is_rmb) { lock = &lgr->rmbs_lock; + buf_llist = &lgr->rmbs_free[bufsize_comp]; buf_list = &lgr->rmbs[bufsize_comp]; } else { lock = &lgr->sndbufs_lock; + buf_llist = &lgr->sndbufs_free[bufsize_comp]; buf_list = &lgr->sndbufs[bufsize_comp]; } bufsize = smc_uncompress_bufsize(bufsize_comp); /* check for reusable slot in the link group */ - buf_desc = smc_buf_get_slot(bufsize_comp, lock, buf_list); + buf_desc = smc_buf_get_slot_free(buf_llist); if (buf_desc) { buf_desc->is_dma_need_sync = 0; SMC_STAT_RMB_SIZE(smc, is_smcd, is_rmb, bufsize); @@ -2412,7 +2421,8 @@ static int __smc_buf_create(struct smc_sock *smc, bool is_smcd, bool is_rmb) SMC_STAT_RMB_ALLOC(smc, is_smcd, is_rmb); SMC_STAT_RMB_SIZE(smc, is_smcd, is_rmb, bufsize); - buf_desc->used = 1; + WRITE_ONCE(buf_desc->used, 1); + WRITE_ONCE(buf_desc->bufsiz_comp, bufsize_comp); down_write(lock); list_add(&buf_desc->list, buf_list); up_write(lock); diff --git a/net/smc/smc_core.h b/net/smc/smc_core.h index d93cf51dbd7c..32ff6a5f076c 100644 --- a/net/smc/smc_core.h +++ b/net/smc/smc_core.h @@ -188,10 +188,12 @@ struct smc_link { /* tx/rx buffer list element for sndbufs list and rmbs list of a lgr */ struct smc_buf_desc { struct list_head list; + struct llist_node llist; void *cpu_addr; /* virtual address of buffer */ struct page *pages; int len; /* length of buffer */ u32 used; /* currently used / unused */ + int bufsiz_comp; union { struct { /* SMC-R */ struct sg_table sgt[SMC_LINKS_PER_LGR_MAX]; @@ -278,8 +280,10 @@ struct smc_link_group { unsigned short vlan_id; /* vlan id of link group */ struct list_head sndbufs[SMC_RMBE_SIZES];/* tx buffers */ + struct llist_head sndbufs_free[SMC_RMBE_SIZES]; /* tx buffer free list */ struct rw_semaphore sndbufs_lock; /* protects tx buffers */ struct list_head rmbs[SMC_RMBE_SIZES]; /* rx buffers */ + struct llist_head rmbs_free[SMC_RMBE_SIZES]; /* rx buffer free list */ struct rw_semaphore rmbs_lock; /* protects rx buffers */ u8 id[SMC_LGR_ID_SIZE]; /* unique lgr id */