From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34669) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZsQwf-0000qi-De for qemu-devel@nongnu.org; Sat, 31 Oct 2015 03:51:26 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZsQwa-00010r-Ca for qemu-devel@nongnu.org; Sat, 31 Oct 2015 03:51:25 -0400 Received: from mga14.intel.com ([192.55.52.115]:31368) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZsQwa-00010c-6A for qemu-devel@nongnu.org; Sat, 31 Oct 2015 03:51:20 -0400 References: <1446184587-142784-1-git-send-email-guangrong.xiao@linux.intel.com> <1446184587-142784-9-git-send-email-guangrong.xiao@linux.intel.com> <563378E1.5000101@virtuozzo.com> From: Xiao Guangrong Message-ID: <56347167.3060206@linux.intel.com> Date: Sat, 31 Oct 2015 15:44:39 +0800 MIME-Version: 1.0 In-Reply-To: <563378E1.5000101@virtuozzo.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v6 08/33] exec: allow memory to be allocated from any kind of path List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Vladimir Sementsov-Ogievskiy , pbonzini@redhat.com, imammedo@redhat.com Cc: ehabkost@redhat.com, kvm@vger.kernel.org, mst@redhat.com, gleb@kernel.org, mtosatti@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com, dan.j.williams@intel.com, rth@twiddle.net On 10/30/2015 10:04 PM, Vladimir Sementsov-Ogievskiy wrote: > On 30.10.2015 08:56, Xiao Guangrong wrote: >> Currently file_ram_alloc() is designed for hugetlbfs, however, the memory >> of nvdimm can come from either raw pmem device eg, /dev/pmem, or the file >> locates at DAX enabled filesystem >> >> So this patch let it work on any kind of path >> >> Signed-off-by: Xiao Guangrong >> --- >> exec.c | 56 +++++++++++++++++--------------------------------------- >> 1 file changed, 17 insertions(+), 39 deletions(-) >> >> diff --git a/exec.c b/exec.c >> index 8af2570..3ca7e50 100644 >> --- a/exec.c >> +++ b/exec.c >> @@ -1174,32 +1174,6 @@ void qemu_mutex_unlock_ramlist(void) >> } >> #ifdef __linux__ >> - >> -#include >> - >> -#define HUGETLBFS_MAGIC 0x958458f6 >> - >> -static long gethugepagesize(const char *path, Error **errp) >> -{ >> - struct statfs fs; >> - int ret; >> - >> - do { >> - ret = statfs(path, &fs); >> - } while (ret != 0 && errno == EINTR); >> - >> - if (ret != 0) { >> - error_setg_errno(errp, errno, "failed to get page size of file %s", >> - path); >> - return 0; >> - } >> - >> - if (fs.f_type != HUGETLBFS_MAGIC) >> - fprintf(stderr, "Warning: path not on HugeTLBFS: %s\n", path); >> - >> - return fs.f_bsize; >> -} >> - >> static void *file_ram_alloc(RAMBlock *block, >> ram_addr_t memory, >> const char *path, >> @@ -1210,20 +1184,24 @@ static void *file_ram_alloc(RAMBlock *block, >> char *c; >> void *area; >> int fd; >> - uint64_t hpagesize; >> - Error *local_err = NULL; >> + uint64_t pagesize; >> - hpagesize = gethugepagesize(path, &local_err); >> - if (local_err) { >> - error_propagate(errp, local_err); >> + pagesize = qemu_file_get_page_size(path); >> + if (!pagesize) { >> + error_setg(errp, "can't get page size for %s", path); >> goto error; >> } >> - block->mr->align = hpagesize; >> - if (memory < hpagesize) { >> + if (pagesize == getpagesize()) { >> + fprintf(stderr, "Memory is not allocated from HugeTlbfs.\n"); >> + } > > It is strange to see this warning every time. > > Shouldn't the differentiation be done explicitly in command line? May be separate option mem-tlb, or > separate flag tlbfs=on, or for new feature - new option mem-file, or prefixes for paths (tlbfs://, > file://).. Or the other way to not mix things but split them. This is just a reminder to users. Currently Qemu do not stop user to append a regular file for its backend memory, particularly, hugetlbfs is not the only way to use HugePage for the THP-enabled system. We can implement your idea as a independent patchset in the future.