From c465bba2c90a810f6e71e4f2646b1b4ee4b478de Mon Sep 17 00:00:00 2001 From: piaojun Date: Fri, 16 Aug 2019 11:42:21 +0800 Subject: [PATCH] virtiofsd: use fuse_buf_writev to replace fuse_buf_write for better performance MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit fuse_buf_writev() only handles the normal write in which src is buffer and dest is fd. Specially if src buffer represents guest physical address that can't be mapped by the daemon process, IO must be bounced back to the VMM to do it by fuse_buf_copy(). Signed-off-by: Jun Piao Suggested-by: Dr. David Alan Gilbert Suggested-by: Stefan Hajnoczi Reviewed-by: Daniel P. Berrangé Signed-off-by: Dr. David Alan Gilbert --- tools/virtiofsd/buffer.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/tools/virtiofsd/buffer.c b/tools/virtiofsd/buffer.c index 37befebac2..27c1377f22 100644 --- a/tools/virtiofsd/buffer.c +++ b/tools/virtiofsd/buffer.c @@ -34,7 +34,6 @@ size_t fuse_buf_size(const struct fuse_bufvec *bufv) return size; } -__attribute__((unused)) static ssize_t fuse_buf_writev(struct fuse_buf *out_buf, struct fuse_bufvec *in_buf) { @@ -262,12 +261,29 @@ static int fuse_bufvec_advance(struct fuse_bufvec *bufv, size_t len) ssize_t fuse_buf_copy(struct fuse_bufvec *dstv, struct fuse_bufvec *srcv) { - size_t copied = 0; + size_t copied = 0, i; if (dstv == srcv) { return fuse_buf_size(dstv); } + /* + * use writev to improve bandwidth when all the + * src buffers already mapped by the daemon + * process + */ + for (i = 0; i < srcv->count; i++) { + if (srcv->buf[i].flags & FUSE_BUF_IS_FD) { + break; + } + } + if ((i == srcv->count) && (dstv->count == 1) && + (dstv->idx == 0) && + (dstv->buf[0].flags & FUSE_BUF_IS_FD)) { + dstv->buf[0].pos += dstv->off; + return fuse_buf_writev(&dstv->buf[0], srcv); + } + for (;;) { const struct fuse_buf *src = fuse_bufvec_current(srcv); const struct fuse_buf *dst = fuse_bufvec_current(dstv);