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From: | Paolo Bonzini |
Subject: | Re: [Qemu-devel] [PATCH v2 03/15] sheepdog: move coroutine send/recv function to generic code |
Date: | Sat, 17 Sep 2011 16:49:22 +0200 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:6.0.2) Gecko/20110906 Thunderbird/6.0.2 |
On 09/17/2011 08:29 AM, MORITA Kazutaka wrote:
> +#else > + struct iovec *p = iov; > + ret = 0; > + while (iovlen> 0) { > + int rc; > + if (do_sendv) { > + rc = send(sockfd, p->iov_base, p->iov_len, 0); > + } else { > + rc = qemu_recv(sockfd, p->iov_base, p->iov_len, 0); > + } > + if (rc == -1) { > + if (errno == EINTR) { > + continue; > + } > + if (ret == 0) { > + ret = -1; > + } > + break; > + } > + iovlen--, p++; > + ret += rc; > + }This code can be called inside coroutines with a non-blocking fd, so should we avoid busy waiting?
It doesn't busy wait, it exits with EAGAIN. I'll squash in here the first hunk of patch 4, which is needed.
qemu_co_recvv already handles reads that return zero, unlike sheepdog's do_readv_writev. I probably moved it there inadvertently while moving code around to cutils.c, but in order to fix qemu-ga I need to create a new file qemu-coroutine-io.c.
Kevin, do you want me to resubmit everything, or are you going to apply some more patches to the block branch (5 to 12 should be fine)?
Paolo
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