From dcaf446ebda5d87e05eb41cdbafb7ae4a7cc4a62 Mon Sep 17 00:00:00 2001 From: Xiao Guangrong Date: Fri, 30 Mar 2018 15:51:20 +0800 Subject: migration: stop compression to allocate and free memory frequently Current code uses compress2() to compress memory which manages memory internally, that causes huge memory is allocated and freed very frequently More worse, frequently returning memory to kernel will flush TLBs and trigger invalidation callbacks on mmu-notification which interacts with KVM MMU, that dramatically reduce the performance of VM So, we maintain the memory by ourselves and reuse it for each compression Reviewed-by: Peter Xu Reviewed-by: Jiang Biao Signed-off-by: Xiao Guangrong Message-Id: <20180330075128.26919-3-xiaoguangrong@tencent.com> Signed-off-by: Dr. David Alan Gilbert --- migration/qemu-file.c | 39 ++++++++++++++++++++++++++++++++------- 1 file changed, 32 insertions(+), 7 deletions(-) (limited to 'migration/qemu-file.c') diff --git a/migration/qemu-file.c b/migration/qemu-file.c index bb63c779cc..bafe3a0c0d 100644 --- a/migration/qemu-file.c +++ b/migration/qemu-file.c @@ -658,8 +658,32 @@ uint64_t qemu_get_be64(QEMUFile *f) return v; } -/* Compress size bytes of data start at p with specific compression - * level and store the compressed data to the buffer of f. +/* return the size after compression, or negative value on error */ +static int qemu_compress_data(z_stream *stream, uint8_t *dest, size_t dest_len, + const uint8_t *source, size_t source_len) +{ + int err; + + err = deflateReset(stream); + if (err != Z_OK) { + return -1; + } + + stream->avail_in = source_len; + stream->next_in = (uint8_t *)source; + stream->avail_out = dest_len; + stream->next_out = dest; + + err = deflate(stream, Z_FINISH); + if (err != Z_STREAM_END) { + return -1; + } + + return stream->next_out - dest; +} + +/* Compress size bytes of data start at p and store the compressed + * data to the buffer of f. * * When f is not writable, return -1 if f has no space to save the * compressed data. @@ -667,9 +691,8 @@ uint64_t qemu_get_be64(QEMUFile *f) * do fflush first, if f still has no space to save the compressed * data, return -1. */ - -ssize_t qemu_put_compression_data(QEMUFile *f, const uint8_t *p, size_t size, - int level) +ssize_t qemu_put_compression_data(QEMUFile *f, z_stream *stream, + const uint8_t *p, size_t size) { ssize_t blen = IO_BUF_SIZE - f->buf_index - sizeof(int32_t); @@ -683,8 +706,10 @@ ssize_t qemu_put_compression_data(QEMUFile *f, const uint8_t *p, size_t size, return -1; } } - if (compress2(f->buf + f->buf_index + sizeof(int32_t), (uLongf *)&blen, - (Bytef *)p, size, level) != Z_OK) { + + blen = qemu_compress_data(stream, f->buf + f->buf_index + sizeof(int32_t), + blen, p, size); + if (blen < 0) { error_report("Compress Failed!"); return 0; } -- cgit v1.2.3-59-g8ed1b