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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 84D81CFB440 for ; Mon, 7 Oct 2024 08:19:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=M9UD9Uv2SyqOTx2EFMg4j1WlT+YHrRtigGkwkbYfuDE=; b=PuX0WEkp1YsS8sNIeEb3sI+8ji 3JnIHxGVtkRfP41vDLgQX6AXOJRs1YmZ3RHe2JJLHXTwbmX0vgknJ55hDv6oXOYHTqLWHHjObYsgq 57urKsR7BPmBazjKTvTrLYIvENkmS58inYFebre1nfHPG4+mYwUb1HSv6mBkEhVqeV3mmwwwEYrT2 ppc+N46M9fjRlW55BeJNbHn5PJpq7Y8CeDzl+0vxVRrEDi9JsqZjg3AbkIonVIjoasncHARW4boha v9xN5H69SxEd8qozq5llkYdV5uvg5ydLLErSmZ1O1TkJxKvaG6zA7tyhHp3hMH7Iny45j8Pt+sLoa OM+Zr+GQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1sxixv-00000001ikd-3TFF; Mon, 07 Oct 2024 08:19:39 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1sxhoF-00000001WpR-1ldF for linux-nvme@lists.infradead.org; Mon, 07 Oct 2024 07:05:36 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 95DD2227A8E; Mon, 7 Oct 2024 09:05:31 +0200 (CEST) Date: Mon, 7 Oct 2024 09:05:31 +0200 From: Christoph Hellwig To: Guixin Liu Cc: hch@lst.de, sagi@grimberg.me, kch@nvidia.com, linux-nvme@lists.infradead.org Subject: Re: [PATCH] nvmet-rdma: use sbitmap to replace rsp free list Message-ID: <20241007070530.GB1477@lst.de> References: <20240925105100.88797-1-kanie@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240925105100.88797-1-kanie@linux.alibaba.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241007_000535_629946_0DC97BC7 X-CRM114-Status: GOOD ( 17.20 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Wed, Sep 25, 2024 at 06:51:00PM +0800, Guixin Liu wrote: > We can use sbitmap to manage all the nvmet_rdma_rsp instead of using > free lists and spinlock, and we can use an additional tag to > determine whether the nvmet_rdma_rsp is extra allocated. Can you explain why? I guess it's better performance for some definition of "performance", but it would be great to state that here, preferably including numbers. > static int nvmet_rdma_alloc_rsp(struct nvmet_rdma_device *ndev, > - struct nvmet_rdma_rsp *r); > + struct nvmet_rdma_rsp *r, > + int tag); Nit: take can go on the line above. > - ret = nvmet_rdma_alloc_rsp(queue->dev, rsp); > + ret = nvmet_rdma_alloc_rsp(queue->dev, rsp, -1); Please add a symbolic name (NVME_RDMA_RSP_DYNAMIC?) for the magic -1 tag. > @@ -241,17 +236,13 @@ nvmet_rdma_get_rsp(struct nvmet_rdma_queue *queue) > static inline void > nvmet_rdma_put_rsp(struct nvmet_rdma_rsp *rsp) > { > - unsigned long flags; > - > - if (unlikely(rsp->allocated)) { > + if (unlikely(rsp->tag < 0)) { .. and use it here. Otherwise this looks reasonable to me.