From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id B27CC2806DC for ; Fri, 19 May 2017 09:05:45 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id h76so13314974pfh.15 for ; Fri, 19 May 2017 06:05:45 -0700 (PDT) Received: from bombadil.infradead.org (bombadil.infradead.org. [65.50.211.133]) by mx.google.com with ESMTPS id o82si8318559pfi.82.2017.05.19.06.05.44 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 19 May 2017 06:05:44 -0700 (PDT) Date: Fri, 19 May 2017 06:05:41 -0700 From: Christoph Hellwig Subject: Re: [PATCH] ib/core: not to set page dirty bit if it's already set. Message-ID: <20170519130541.GA8017@infradead.org> References: <20170518233353.14370-1-qing.huang@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170518233353.14370-1-qing.huang@oracle.com> Sender: owner-linux-mm@kvack.org List-ID: To: Qing Huang Cc: linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, dledford@redhat.com, sean.hefty@intel.com, artemyko@mellanox.com, linux-mm@kvack.org On Thu, May 18, 2017 at 04:33:53PM -0700, Qing Huang wrote: > This change will optimize kernel memory deregistration operations. > __ib_umem_release() used to call set_page_dirty_lock() against every > writable page in its memory region. Its purpose is to keep data > synced between CPU and DMA device when swapping happens after mem > deregistration ops. Now we choose not to set page dirty bit if it's > already set by kernel prior to calling __ib_umem_release(). This > reduces memory deregistration time by half or even more when we ran > application simulation test program. As far as I can tell this code doesn't even need set_page_dirty_lock and could just use set_page_dirty > > Signed-off-by: Qing Huang > --- > drivers/infiniband/core/umem.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c > index 3dbf811..21e60b1 100644 > --- a/drivers/infiniband/core/umem.c > +++ b/drivers/infiniband/core/umem.c > @@ -58,7 +58,7 @@ static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int d > for_each_sg(umem->sg_head.sgl, sg, umem->npages, i) { > > page = sg_page(sg); > - if (umem->writable && dirty) > + if (!PageDirty(page) && umem->writable && dirty) > set_page_dirty_lock(page); > put_page(page); > } > -- > 2.9.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-rdma" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html ---end quoted text--- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org