From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH v4 2/3] Support adding a file to qemu's ram allocation Date: Mon, 12 Apr 2010 23:38:05 +0300 Message-ID: <4BC384AD.1090500@redhat.com> References: <1270680720-8457-1-git-send-email-cam@cs.ualberta.ca> <1270680720-8457-2-git-send-email-cam@cs.ualberta.ca> <1270680720-8457-3-git-send-email-cam@cs.ualberta.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, qemu-devel@nongnu.org To: Cam Macdonell Return-path: Received: from mx1.redhat.com ([209.132.183.28]:48306 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753489Ab0DLUiK (ORCPT ); Mon, 12 Apr 2010 16:38:10 -0400 In-Reply-To: <1270680720-8457-3-git-send-email-cam@cs.ualberta.ca> Sender: kvm-owner@vger.kernel.org List-ID: On 04/08/2010 01:51 AM, Cam Macdonell wrote: > This avoids the need of using qemu_ram_alloc and mmap with MAP_FIXED to map a > host file into guest RAM. This function mmaps the opened file anywhere and adds > the memory to the ram blocks. > > Usage is > > qemu_ram_mmap(fd, size, MAP_SHARED, offset); > --- > cpu-common.h | 1 + > exec.c | 33 +++++++++++++++++++++++++++++++++ > 2 files changed, 34 insertions(+), 0 deletions(-) > > diff --git a/cpu-common.h b/cpu-common.h > index 49c7fb3..87c82fc 100644 > --- a/cpu-common.h > +++ b/cpu-common.h > @@ -32,6 +32,7 @@ static inline void cpu_register_physical_memory(target_phys_addr_t start_addr, > } > > ram_addr_t cpu_get_physical_page_desc(target_phys_addr_t addr); > +ram_addr_t qemu_ram_mmap(int, ram_addr_t, int, int); > Use prototypes with argument names please. That's not the style around it, but that's bad style. > > +ram_addr_t qemu_ram_mmap(int fd, ram_addr_t size, int flags, int offset) > off_t offset > +{ > + RAMBlock *new_block; > + > + size = TARGET_PAGE_ALIGN(size); > + new_block = qemu_malloc(sizeof(*new_block)); > + > + // map the file passed as a parameter to be this part of memory > /* comments */ > + new_block->host = mmap(0, size, PROT_READ|PROT_WRITE, flags, fd, offset); > Error checking. > + > +#ifdef MADV_MERGEABLE > + madvise(new_block->host, size, MADV_MERGEABLE); > +#endif > Won't work (ksm only merges anonymous pages), but keep it there in case it learns about pagecache. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic. From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1O1QOc-0006li-CE for qemu-devel@nongnu.org; Mon, 12 Apr 2010 16:38:14 -0400 Received: from [140.186.70.92] (port=34845 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O1QOZ-0006kc-On for qemu-devel@nongnu.org; Mon, 12 Apr 2010 16:38:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1O1QOY-0002P9-1a for qemu-devel@nongnu.org; Mon, 12 Apr 2010 16:38:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:10074) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1O1QOX-0002P3-MY for qemu-devel@nongnu.org; Mon, 12 Apr 2010 16:38:09 -0400 Message-ID: <4BC384AD.1090500@redhat.com> Date: Mon, 12 Apr 2010 23:38:05 +0300 From: Avi Kivity MIME-Version: 1.0 References: <1270680720-8457-1-git-send-email-cam@cs.ualberta.ca> <1270680720-8457-2-git-send-email-cam@cs.ualberta.ca> <1270680720-8457-3-git-send-email-cam@cs.ualberta.ca> In-Reply-To: <1270680720-8457-3-git-send-email-cam@cs.ualberta.ca> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: [PATCH v4 2/3] Support adding a file to qemu's ram allocation List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Cam Macdonell Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org On 04/08/2010 01:51 AM, Cam Macdonell wrote: > This avoids the need of using qemu_ram_alloc and mmap with MAP_FIXED to map a > host file into guest RAM. This function mmaps the opened file anywhere and adds > the memory to the ram blocks. > > Usage is > > qemu_ram_mmap(fd, size, MAP_SHARED, offset); > --- > cpu-common.h | 1 + > exec.c | 33 +++++++++++++++++++++++++++++++++ > 2 files changed, 34 insertions(+), 0 deletions(-) > > diff --git a/cpu-common.h b/cpu-common.h > index 49c7fb3..87c82fc 100644 > --- a/cpu-common.h > +++ b/cpu-common.h > @@ -32,6 +32,7 @@ static inline void cpu_register_physical_memory(target_phys_addr_t start_addr, > } > > ram_addr_t cpu_get_physical_page_desc(target_phys_addr_t addr); > +ram_addr_t qemu_ram_mmap(int, ram_addr_t, int, int); > Use prototypes with argument names please. That's not the style around it, but that's bad style. > > +ram_addr_t qemu_ram_mmap(int fd, ram_addr_t size, int flags, int offset) > off_t offset > +{ > + RAMBlock *new_block; > + > + size = TARGET_PAGE_ALIGN(size); > + new_block = qemu_malloc(sizeof(*new_block)); > + > + // map the file passed as a parameter to be this part of memory > /* comments */ > + new_block->host = mmap(0, size, PROT_READ|PROT_WRITE, flags, fd, offset); > Error checking. > + > +#ifdef MADV_MERGEABLE > + madvise(new_block->host, size, MADV_MERGEABLE); > +#endif > Won't work (ksm only merges anonymous pages), but keep it there in case it learns about pagecache. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.