From af74db72d33e4776d7d1430b57d0bf065a6f03df Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 8 Apr 2013 13:29:54 +0200 Subject: [PATCH 1/4] migration: set f->is_write and flush in add_to_iovec Signed-off-by: Paolo Bonzini Signed-off-by: Juan Quintela --- savevm.c | 25 +++++++++---------------- 1 file changed, 9 insertions(+), 16 deletions(-) diff --git a/savevm.c b/savevm.c index b1d8988c78..c952c41057 100644 --- a/savevm.c +++ b/savevm.c @@ -631,6 +631,11 @@ static void add_to_iovec(QEMUFile *f, const uint8_t *buf, int size) f->iov[f->iovcnt].iov_base = (uint8_t *)buf; f->iov[f->iovcnt++].iov_len = size; } + + f->is_write = 1; + if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) { + qemu_fflush(f); + } } void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, int size) @@ -645,14 +650,8 @@ void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, int size) abort(); } - add_to_iovec(f, buf, size); - - f->is_write = 1; f->bytes_xfer += size; - - if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) { - qemu_fflush(f); - } + add_to_iovec(f, buf, size); } void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size) @@ -674,7 +673,6 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size) if (l > size) l = size; memcpy(f->buf + f->buf_index, buf, l); - f->is_write = 1; f->buf_index += l; qemu_put_buffer_async(f, f->buf + (f->buf_index - l), l); if (qemu_file_get_error(f)) { @@ -697,15 +695,10 @@ void qemu_put_byte(QEMUFile *f, int v) abort(); } - f->buf[f->buf_index++] = v; - f->is_write = 1; + f->buf[f->buf_index] = v; f->bytes_xfer++; - - add_to_iovec(f, f->buf + (f->buf_index - 1), 1); - - if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) { - qemu_fflush(f); - } + add_to_iovec(f, f->buf + f->buf_index, 1); + f->buf_index++; } static void qemu_file_skip(QEMUFile *f, int size) From 7ce51f1b8157a2aa6bd3945bba9904442d3c3cdd Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 8 Apr 2013 13:29:55 +0200 Subject: [PATCH 2/4] migration: use a single I/O operation when writev_buffer is not defined The recent patches to use vectored I/O for RAM migration caused a regression in savevm speed. To restore previous performance, add data to the buffer in qemu_put_buffer_async whenever writev_buffer is not available in the QEMUFile. Signed-off-by: Paolo Bonzini Signed-off-by: Juan Quintela --- savevm.c | 49 ++++++++++++++++++++++++++++++++++--------------- 1 file changed, 34 insertions(+), 15 deletions(-) diff --git a/savevm.c b/savevm.c index c952c41057..b32e0a7fa1 100644 --- a/savevm.c +++ b/savevm.c @@ -525,27 +525,24 @@ static void qemu_file_set_error(QEMUFile *f, int ret) static void qemu_fflush(QEMUFile *f) { ssize_t ret = 0; - int i = 0; if (!f->ops->writev_buffer && !f->ops->put_buffer) { return; } - if (f->is_write && f->iovcnt > 0) { + if (f->is_write) { if (f->ops->writev_buffer) { - ret = f->ops->writev_buffer(f->opaque, f->iov, f->iovcnt); - if (ret >= 0) { - f->pos += ret; + if (f->iovcnt > 0) { + ret = f->ops->writev_buffer(f->opaque, f->iov, f->iovcnt); } } else { - for (i = 0; i < f->iovcnt && ret >= 0; i++) { - ret = f->ops->put_buffer(f->opaque, f->iov[i].iov_base, f->pos, - f->iov[i].iov_len); - if (ret >= 0) { - f->pos += ret; - } + if (f->buf_index > 0) { + ret = f->ops->put_buffer(f->opaque, f->buf, f->pos, f->buf_index); } } + if (ret >= 0) { + f->pos += ret; + } f->buf_index = 0; f->iovcnt = 0; } @@ -640,6 +637,11 @@ static void add_to_iovec(QEMUFile *f, const uint8_t *buf, int size) void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, int size) { + if (!f->ops->writev_buffer) { + qemu_put_buffer(f, buf, size); + return; + } + if (f->last_error) { return; } @@ -673,8 +675,17 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size) if (l > size) l = size; memcpy(f->buf + f->buf_index, buf, l); - f->buf_index += l; - qemu_put_buffer_async(f, f->buf + (f->buf_index - l), l); + f->bytes_xfer += size; + if (f->ops->writev_buffer) { + add_to_iovec(f, f->buf + f->buf_index, l); + f->buf_index += l; + } else { + f->is_write = 1; + f->buf_index += l; + if (f->buf_index == IO_BUF_SIZE) { + qemu_fflush(f); + } + } if (qemu_file_get_error(f)) { break; } @@ -697,8 +708,16 @@ void qemu_put_byte(QEMUFile *f, int v) f->buf[f->buf_index] = v; f->bytes_xfer++; - add_to_iovec(f, f->buf + f->buf_index, 1); - f->buf_index++; + if (f->ops->writev_buffer) { + add_to_iovec(f, f->buf + f->buf_index, 1); + f->buf_index++; + } else { + f->is_write = 1; + f->buf_index++; + if (f->buf_index == IO_BUF_SIZE) { + qemu_fflush(f); + } + } } static void qemu_file_skip(QEMUFile *f, int size) From d9658c4732a88efc42ab43bda69ae9f62559205b Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 8 Apr 2013 13:29:56 +0200 Subject: [PATCH 3/4] migration: drop is_write complications The same QEMUFile is never used for both read and write. Simplify the logic to simply look for presence or absence of the right ops. Signed-off-by: Paolo Bonzini Signed-off-by: Juan Quintela --- savevm.c | 68 +++++++++++++++++--------------------------------------- 1 file changed, 20 insertions(+), 48 deletions(-) diff --git a/savevm.c b/savevm.c index b32e0a7fa1..a2f6bc0402 100644 --- a/savevm.c +++ b/savevm.c @@ -119,7 +119,6 @@ void qemu_announce_self(void) struct QEMUFile { const QEMUFileOps *ops; void *opaque; - int is_write; int64_t bytes_xfer; int64_t xfer_limit; @@ -500,7 +499,6 @@ QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops) f->opaque = opaque; f->ops = ops; - f->is_write = 0; return f; } @@ -516,6 +514,11 @@ static void qemu_file_set_error(QEMUFile *f, int ret) } } +static inline bool qemu_file_is_writable(QEMUFile *f) +{ + return f->ops->writev_buffer || f->ops->put_buffer; +} + /** * Flushes QEMUFile buffer * @@ -526,26 +529,24 @@ static void qemu_fflush(QEMUFile *f) { ssize_t ret = 0; - if (!f->ops->writev_buffer && !f->ops->put_buffer) { + if (!qemu_file_is_writable(f)) { return; } - if (f->is_write) { - if (f->ops->writev_buffer) { - if (f->iovcnt > 0) { - ret = f->ops->writev_buffer(f->opaque, f->iov, f->iovcnt); - } - } else { - if (f->buf_index > 0) { - ret = f->ops->put_buffer(f->opaque, f->buf, f->pos, f->buf_index); - } + if (f->ops->writev_buffer) { + if (f->iovcnt > 0) { + ret = f->ops->writev_buffer(f->opaque, f->iov, f->iovcnt); } - if (ret >= 0) { - f->pos += ret; + } else { + if (f->buf_index > 0) { + ret = f->ops->put_buffer(f->opaque, f->buf, f->pos, f->buf_index); } - f->buf_index = 0; - f->iovcnt = 0; } + if (ret >= 0) { + f->pos += ret; + } + f->buf_index = 0; + f->iovcnt = 0; if (ret < 0) { qemu_file_set_error(f, ret); } @@ -556,11 +557,7 @@ static void qemu_fill_buffer(QEMUFile *f) int len; int pending; - if (!f->ops->get_buffer) - return; - - if (f->is_write) - abort(); + assert(!qemu_file_is_writable(f)); pending = f->buf_size - f->buf_index; if (pending > 0) { @@ -629,7 +626,6 @@ static void add_to_iovec(QEMUFile *f, const uint8_t *buf, int size) f->iov[f->iovcnt++].iov_len = size; } - f->is_write = 1; if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) { qemu_fflush(f); } @@ -646,12 +642,6 @@ void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, int size) return; } - if (f->is_write == 0 && f->buf_index > 0) { - fprintf(stderr, - "Attempted to write to buffer while read buffer is not empty\n"); - abort(); - } - f->bytes_xfer += size; add_to_iovec(f, buf, size); } @@ -664,12 +654,6 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size) return; } - if (f->is_write == 0 && f->buf_index > 0) { - fprintf(stderr, - "Attempted to write to buffer while read buffer is not empty\n"); - abort(); - } - while (size > 0) { l = IO_BUF_SIZE - f->buf_index; if (l > size) @@ -680,7 +664,6 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size) add_to_iovec(f, f->buf + f->buf_index, l); f->buf_index += l; } else { - f->is_write = 1; f->buf_index += l; if (f->buf_index == IO_BUF_SIZE) { qemu_fflush(f); @@ -700,19 +683,12 @@ void qemu_put_byte(QEMUFile *f, int v) return; } - if (f->is_write == 0 && f->buf_index > 0) { - fprintf(stderr, - "Attempted to write to buffer while read buffer is not empty\n"); - abort(); - } - f->buf[f->buf_index] = v; f->bytes_xfer++; if (f->ops->writev_buffer) { add_to_iovec(f, f->buf + f->buf_index, 1); f->buf_index++; } else { - f->is_write = 1; f->buf_index++; if (f->buf_index == IO_BUF_SIZE) { qemu_fflush(f); @@ -732,9 +708,7 @@ static int qemu_peek_buffer(QEMUFile *f, uint8_t *buf, int size, size_t offset) int pending; int index; - if (f->is_write) { - abort(); - } + assert(!qemu_file_is_writable(f)); index = f->buf_index + offset; pending = f->buf_size - index; @@ -779,9 +753,7 @@ static int qemu_peek_byte(QEMUFile *f, int offset) { int index = f->buf_index + offset; - if (f->is_write) { - abort(); - } + assert(!qemu_file_is_writable(f)); if (index >= f->buf_size) { qemu_fill_buffer(f); From 4d1172472cdf28a444321ca8b165ce7326eb919e Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 8 Apr 2013 13:29:57 +0200 Subject: [PATCH 4/4] migration: simplify writev vs. non-writev logic Check f->iovcnt in add_to_iovec, f->buf_index in qemu_put_buffer/byte. Signed-off-by: Paolo Bonzini Signed-off-by: Juan Quintela --- savevm.c | 22 +++++++++------------- 1 file changed, 9 insertions(+), 13 deletions(-) diff --git a/savevm.c b/savevm.c index a2f6bc0402..63f4c828a9 100644 --- a/savevm.c +++ b/savevm.c @@ -626,7 +626,7 @@ static void add_to_iovec(QEMUFile *f, const uint8_t *buf, int size) f->iov[f->iovcnt++].iov_len = size; } - if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) { + if (f->iovcnt >= MAX_IOV_SIZE) { qemu_fflush(f); } } @@ -662,12 +662,10 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size) f->bytes_xfer += size; if (f->ops->writev_buffer) { add_to_iovec(f, f->buf + f->buf_index, l); - f->buf_index += l; - } else { - f->buf_index += l; - if (f->buf_index == IO_BUF_SIZE) { - qemu_fflush(f); - } + } + f->buf_index += l; + if (f->buf_index == IO_BUF_SIZE) { + qemu_fflush(f); } if (qemu_file_get_error(f)) { break; @@ -687,12 +685,10 @@ void qemu_put_byte(QEMUFile *f, int v) f->bytes_xfer++; if (f->ops->writev_buffer) { add_to_iovec(f, f->buf + f->buf_index, 1); - f->buf_index++; - } else { - f->buf_index++; - if (f->buf_index == IO_BUF_SIZE) { - qemu_fflush(f); - } + } + f->buf_index++; + if (f->buf_index == IO_BUF_SIZE) { + qemu_fflush(f); } }