[Virtio-fs] [PATCH RFC] virtiofs: improve io bandwidth by replacing pwrite with pwritev
piaojun
piaojun at huawei.com
Wed Aug 7 01:30:20 UTC 2019
Hi Dave,
On 2019/8/7 0:09, Dr. David Alan Gilbert wrote:
> * piaojun (piaojun at huawei.com) wrote:
>> >From my test, write bandwidth will be improved greatly by replacing
>> pwrite with pwritev, and the test result as below:
>>
>> ---
>> pwrite:
>> # fio -direct=1 -time_based -iodepth=64 -rw=randwrite -ioengine=libaio -bs=1M -size=1G -numjob=16 -runtime=30 -group_reporting -name=file -filename=/mnt/virtiofs/file
>> file: (g=0): rw=randwrite, bs=1M-1M/1M-1M/1M-1M, ioengine=libaio, iodepth=64
>> ...
>> fio-2.13
>> Starting 16 processes
>> Jobs: 16 (f=16): [w(16)] [100.0% done] [0KB/886.0MB/0KB /s] [0/886/0 iops] [eta 00m:00s]
>> file: (groupid=0, jobs=16): err= 0: pid=5799: Tue Aug 6 18:48:26 2019
>> write: io=26881MB, bw=916988KB/s, iops=895, runt= 30018msec
>>
>> pwritev:
>> # fio -direct=1 -time_based -iodepth=64 -rw=randwrite -ioengine=libaio -bs=1M -size=1G -numjob=16 -runtime=30 -group_reporting -name=file -filename=/mnt/virtiofs/file
>> file: (g=0): rw=randwrite, bs=1M-1M/1M-1M/1M-1M, ioengine=libaio, iodepth=64
>> ...
>> fio-2.13
>> Starting 16 processes
>> Jobs: 16 (f=16): [w(16)] [100.0% done] [0KB/1793MB/0KB /s] [0/1793/0 iops] [eta 00m:00s]
>> file: (groupid=0, jobs=16): err= 0: pid=6328: Tue Aug 6 18:22:17 2019
>> write: io=52775MB, bw=1758.7MB/s, iops=1758, runt= 30009msec
>
> OK, nice improvements.
>
>> ---
>>
>> This patch introduces writev and pwritev and clean up *fuse_buf_copy*
>> and its related code. I wonder if I'd better split it into two patches
>> or other modification. I'm very glad for your suggestions.
>
> It does need splitting; but I think there are some problems; it seems to
> ignore most of the flags; in particular FUSE_BUF_PHYS_ADDR - I added
> that to handle cases where it was a write() call from one DAX mapped
> file to another. I suspect some of the other flags are relevant as
> well.
Agreed, FUSE_BUF_PHYS_ADDR is needed, and I will fix these problems in
patch v2.
Thanks,
Jun
>
> Dave
>
>
>> Thanks,
>> Jun
>>
>> Signed-off-by: Jun Piao <piaojun at huawei.com>
>> ---
>> contrib/virtiofsd/buffer.c | 310 ++++---------------------------------
>> contrib/virtiofsd/fuse_common.h | 15 +-
>> contrib/virtiofsd/passthrough_ll.c | 2 +-
>> contrib/virtiofsd/seccomp.c | 2 +
>> 4 files changed, 37 insertions(+), 292 deletions(-)
>>
>> diff --git a/contrib/virtiofsd/buffer.c b/contrib/virtiofsd/buffer.c
>> index 655be137..78f8d3e 100644
>> --- a/contrib/virtiofsd/buffer.c
>> +++ b/contrib/virtiofsd/buffer.c
>> @@ -15,6 +15,7 @@
>> #include <unistd.h>
>> #include <errno.h>
>> #include <assert.h>
>> +#include <stdlib.h>
>>
>> size_t fuse_buf_size(const struct fuse_bufvec *bufv)
>> {
>> @@ -31,299 +32,40 @@ size_t fuse_buf_size(const struct fuse_bufvec *bufv)
>> return size;
>> }
>>
>> -static size_t min_size(size_t s1, size_t s2)
>> +ssize_t fuse_buf_writev(fuse_req_t req,
>> + struct fuse_bufvec *out_buf,
>> + struct fuse_bufvec *in_buf,
>> + enum fuse_buf_copy_flags flags)
>> {
>> - return s1 < s2 ? s1 : s2;
>> -}
>> -
>> -static ssize_t fuse_buf_write(const struct fuse_buf *dst, size_t dst_off,
>> - const struct fuse_buf *src, size_t src_off,
>> - size_t len)
>> -{
>> - ssize_t res = 0;
>> - size_t copied = 0;
>> -
>> - assert(!(src->flags & FUSE_BUF_PHYS_ADDR));
>> - while (len) {
>> - if (dst->flags & FUSE_BUF_FD_SEEK) {
>> - res = pwrite(dst->fd, src->mem + src_off, len,
>> - dst->pos + dst_off);
>> - } else {
>> - res = write(dst->fd, src->mem + src_off, len);
>> - }
>> - if (res == -1) {
>> - if (!copied)
>> - return -errno;
>> - break;
>> - }
>> - if (res == 0)
>> - break;
>> -
>> - copied += res;
>> - if (!(dst->flags & FUSE_BUF_FD_RETRY))
>> - break;
>> -
>> - src_off += res;
>> - dst_off += res;
>> - len -= res;
>> - }
>> -
>> - return copied;
>> -}
>> -
>> -static ssize_t fuse_buf_read(const struct fuse_buf *dst, size_t dst_off,
>> - const struct fuse_buf *src, size_t src_off,
>> - size_t len)
>> -{
>> - ssize_t res = 0;
>> - size_t copied = 0;
>> -
>> - while (len) {
>> - if (src->flags & FUSE_BUF_FD_SEEK) {
>> - res = pread(src->fd, dst->mem + dst_off, len,
>> - src->pos + src_off);
>> - } else {
>> - res = read(src->fd, dst->mem + dst_off, len);
>> - }
>> - if (res == -1) {
>> - if (!copied)
>> - return -errno;
>> - break;
>> - }
>> - if (res == 0)
>> - break;
>> -
>> - copied += res;
>> - if (!(src->flags & FUSE_BUF_FD_RETRY))
>> - break;
>> -
>> - dst_off += res;
>> - src_off += res;
>> - len -= res;
>> - }
>> -
>> - return copied;
>> -}
>> -
>> -static ssize_t fuse_buf_fd_to_fd(const struct fuse_buf *dst, size_t dst_off,
>> - const struct fuse_buf *src, size_t src_off,
>> - size_t len)
>> -{
>> - char buf[4096];
>> - struct fuse_buf tmp = {
>> - .size = sizeof(buf),
>> - .flags = 0,
>> - };
>> - ssize_t res;
>> - size_t copied = 0;
>> -
>> - tmp.mem = buf;
>> -
>> - while (len) {
>> - size_t this_len = min_size(tmp.size, len);
>> - size_t read_len;
>> -
>> - res = fuse_buf_read(&tmp, 0, src, src_off, this_len);
>> - if (res < 0) {
>> - if (!copied)
>> - return res;
>> - break;
>> - }
>> - if (res == 0)
>> - break;
>> -
>> - read_len = res;
>> - res = fuse_buf_write(dst, dst_off, &tmp, 0, read_len);
>> - if (res < 0) {
>> - if (!copied)
>> - return res;
>> - break;
>> - }
>> - if (res == 0)
>> - break;
>> -
>> - copied += res;
>> -
>> - if (res < this_len)
>> - break;
>> -
>> - dst_off += res;
>> - src_off += res;
>> - len -= res;
>> - }
>> -
>> - return copied;
>> -}
>> -
>> -#ifdef HAVE_SPLICE
>> -static ssize_t fuse_buf_splice(const struct fuse_buf *dst, size_t dst_off,
>> - const struct fuse_buf *src, size_t src_off,
>> - size_t len, enum fuse_buf_copy_flags flags)
>> -{
>> - int splice_flags = 0;
>> - off_t *srcpos = NULL;
>> - off_t *dstpos = NULL;
>> - off_t srcpos_val;
>> - off_t dstpos_val;
>> - ssize_t res;
>> - size_t copied = 0;
>> -
>> - if (flags & FUSE_BUF_SPLICE_MOVE)
>> - splice_flags |= SPLICE_F_MOVE;
>> - if (flags & FUSE_BUF_SPLICE_NONBLOCK)
>> - splice_flags |= SPLICE_F_NONBLOCK;
>> -
>> - if (src->flags & FUSE_BUF_FD_SEEK) {
>> - srcpos_val = src->pos + src_off;
>> - srcpos = &srcpos_val;
>> - }
>> - if (dst->flags & FUSE_BUF_FD_SEEK) {
>> - dstpos_val = dst->pos + dst_off;
>> - dstpos = &dstpos_val;
>> - }
>> -
>> - while (len) {
>> - res = splice(src->fd, srcpos, dst->fd, dstpos, len,
>> - splice_flags);
>> - if (res == -1) {
>> - if (copied)
>> - break;
>> -
>> - if (errno != EINVAL || (flags & FUSE_BUF_FORCE_SPLICE))
>> - return -errno;
>> -
>> - /* Maybe splice is not supported for this combination */
>> - return fuse_buf_fd_to_fd(dst, dst_off, src, src_off,
>> - len);
>> - }
>> - if (res == 0)
>> - break;
>> -
>> - copied += res;
>> - if (!(src->flags & FUSE_BUF_FD_RETRY) &&
>> - !(dst->flags & FUSE_BUF_FD_RETRY)) {
>> - break;
>> - }
>> -
>> - len -= res;
>> - }
>> -
>> - return copied;
>> -}
>> -#else
>> -static ssize_t fuse_buf_splice(const struct fuse_buf *dst, size_t dst_off,
>> - const struct fuse_buf *src, size_t src_off,
>> - size_t len, enum fuse_buf_copy_flags flags)
>> -{
>> - (void) flags;
>> -
>> - return fuse_buf_fd_to_fd(dst, dst_off, src, src_off, len);
>> -}
>> -#endif
>> -
>> -
>> -static ssize_t fuse_buf_copy_one(fuse_req_t req,
>> - const struct fuse_buf *dst, size_t dst_off,
>> - const struct fuse_buf *src, size_t src_off,
>> - size_t len, enum fuse_buf_copy_flags flags)
>> -{
>> - int src_is_fd = src->flags & FUSE_BUF_IS_FD;
>> - int dst_is_fd = dst->flags & FUSE_BUF_IS_FD;
>> - int src_is_phys = src->flags & FUSE_BUF_PHYS_ADDR;
>> - int dst_is_phys = src->flags & FUSE_BUF_PHYS_ADDR;
>> -
>> - if (src_is_phys && !src_is_fd && dst_is_fd) {
>> - return fuse_virtio_write(req, dst, dst_off, src, src_off, len);
>> - }
>> -
>> - assert(!src_is_phys && !dst_is_phys);
>> - if (!src_is_fd && !dst_is_fd) {
>> - void *dstmem = dst->mem + dst_off;
>> - void *srcmem = src->mem + src_off;
>> + ssize_t res, i, buf_index, iovcnt;
>> + struct iovec * iov;
>> + int fd = out_buf->buf[0].fd;
>> + off_t pos = out_buf->buf[0].pos;
>>
>> - if (dstmem != srcmem) {
>> - if (dstmem + len <= srcmem || srcmem + len <= dstmem)
>> - memcpy(dstmem, srcmem, len);
>> - else
>> - memmove(dstmem, srcmem, len);
>> - }
>> -
>> - return len;
>> - } else if (!src_is_fd) {
>> - return fuse_buf_write(dst, dst_off, src, src_off, len);
>> - } else if (!dst_is_fd) {
>> - return fuse_buf_read(dst, dst_off, src, src_off, len);
>> - } else if (flags & FUSE_BUF_NO_SPLICE) {
>> - return fuse_buf_fd_to_fd(dst, dst_off, src, src_off, len);
>> - } else {
>> - return fuse_buf_splice(dst, dst_off, src, src_off, len, flags);
>> - }
>> -}
>> -
>> -static const struct fuse_buf *fuse_bufvec_current(struct fuse_bufvec *bufv)
>> -{
>> - if (bufv->idx < bufv->count)
>> - return &bufv->buf[bufv->idx];
>> + if (in_buf->count > 2)
>> + iovcnt = in_buf->count - 1;
>> else
>> - return NULL;
>> -}
>> + iovcnt = 1;
>>
>> -static int fuse_bufvec_advance(struct fuse_bufvec *bufv, size_t len)
>> -{
>> - const struct fuse_buf *buf = fuse_bufvec_current(bufv);
>> + iov = malloc(iovcnt * sizeof(struct iovec));
>> + if (!iov)
>> + return -ENOMEM;
>>
>> - bufv->off += len;
>> - assert(bufv->off <= buf->size);
>> - if (bufv->off == buf->size) {
>> - assert(bufv->idx < bufv->count);
>> - bufv->idx++;
>> - if (bufv->idx == bufv->count)
>> - return 0;
>> - bufv->off = 0;
>> + for (i = 0, buf_index = 1; i < iovcnt; i++, buf_index++) {
>> + iov[i].iov_base = in_buf->buf[buf_index].mem;
>> + iov[i].iov_len = in_buf->buf[buf_index].size;
>> }
>> - return 1;
>> -}
>>
>> -ssize_t fuse_buf_copy(fuse_req_t req, struct fuse_bufvec *dstv, struct fuse_bufvec *srcv,
>> - enum fuse_buf_copy_flags flags)
>> -{
>> - size_t copied = 0;
>> -
>> - if (dstv == srcv)
>> - return fuse_buf_size(dstv);
>> -
>> - for (;;) {
>> - const struct fuse_buf *src = fuse_bufvec_current(srcv);
>> - const struct fuse_buf *dst = fuse_bufvec_current(dstv);
>> - size_t src_len;
>> - size_t dst_len;
>> - size_t len;
>> - ssize_t res;
>> -
>> - if (src == NULL || dst == NULL)
>> - break;
>> -
>> - src_len = src->size - srcv->off;
>> - dst_len = dst->size - dstv->off;
>> - len = min_size(src_len, dst_len);
>> -
>> - res = fuse_buf_copy_one(req, dst, dstv->off, src, srcv->off, len, flags);
>> - if (res < 0) {
>> - if (!copied)
>> - return res;
>> - break;
>> - }
>> - copied += res;
>> -
>> - if (!fuse_bufvec_advance(srcv, res) ||
>> - !fuse_bufvec_advance(dstv, res))
>> - break;
>> + if (flags & FUSE_BUF_FD_SEEK)
>> + res = pwritev(fd, iov, iovcnt, pos);
>> + else
>> + res = writev(fd, iov, iovcnt);
>>
>> - if (res < len)
>> - break;
>> - }
>> + if (res == -1 || res == 0)
>> + res = -errno;
>>
>> - return copied;
>> + free(iov);
>> + return res;
>> }
>>
>> void *fuse_mbuf_iter_advance(struct fuse_mbuf_iter *iter, size_t len)
>> diff --git a/contrib/virtiofsd/fuse_common.h b/contrib/virtiofsd/fuse_common.h
>> index 001e6d6..c715e52 100644
>> --- a/contrib/virtiofsd/fuse_common.h
>> +++ b/contrib/virtiofsd/fuse_common.h
>> @@ -717,17 +717,18 @@ struct fuse_bufvec {
>> size_t fuse_buf_size(const struct fuse_bufvec *bufv);
>>
>> /**
>> - * Copy data from one buffer vector to another
>> + * Write data from one buffer vector to another
>> *
>> * @param req The request this copy is part of
>> - * @param dst destination buffer vector
>> - * @param src source buffer vector
>> + * @param out_buf destination buffer vector
>> + * @param in_buf source buffer vector
>> * @param flags flags controlling the copy
>> - * @return actual number of bytes copied or -errno on error
>> + * @return actual number of bytes written or -errno on error
>> */
>> -ssize_t fuse_buf_copy(fuse_req_t req,
>> - struct fuse_bufvec *dst, struct fuse_bufvec *src,
>> - enum fuse_buf_copy_flags flags);
>> +ssize_t fuse_buf_writev(fuse_req_t req,
>> + struct fuse_bufvec *out_buf,
>> + struct fuse_bufvec *in_buf,
>> + enum fuse_buf_copy_flags flags);
>>
>> /**
>> * Memory buffer iterator
>> diff --git a/contrib/virtiofsd/passthrough_ll.c b/contrib/virtiofsd/passthrough_ll.c
>> index cc9c175..3082683 100644
>> --- a/contrib/virtiofsd/passthrough_ll.c
>> +++ b/contrib/virtiofsd/passthrough_ll.c
>> @@ -2023,7 +2023,7 @@ static void lo_write_buf(fuse_req_t req, fuse_ino_t ino,
>> fuse_debug("lo_write_buf(ino=%" PRIu64 ", size=%zd, off=%lu)\n",
>> ino, out_buf.buf[0].size, (unsigned long) off);
>>
>> - res = fuse_buf_copy(req, &out_buf, in_buf, 0);
>> + res = fuse_buf_writev(req, &out_buf, in_buf, out_buf.buf[0].flags);
>> if(res < 0) {
>> fuse_reply_err(req, -res);
>> } else {
>> diff --git a/contrib/virtiofsd/seccomp.c b/contrib/virtiofsd/seccomp.c
>> index 5f1c873..4bba30b 100644
>> --- a/contrib/virtiofsd/seccomp.c
>> +++ b/contrib/virtiofsd/seccomp.c
>> @@ -60,6 +60,7 @@ static const int syscall_whitelist[] = {
>> SCMP_SYS(ppoll),
>> SCMP_SYS(prctl), /* TODO restrict to just PR_SET_NAME? */
>> SCMP_SYS(preadv),
>> + SCMP_SYS(pwritev),
>> SCMP_SYS(pwrite64),
>> SCMP_SYS(read),
>> SCMP_SYS(readlinkat),
>> @@ -78,6 +79,7 @@ static const int syscall_whitelist[] = {
>> SCMP_SYS(unlinkat),
>> SCMP_SYS(utimensat),
>> SCMP_SYS(write),
>> + SCMP_SYS(writev),
>> };
>>
>> /* Syscalls used when --syslog is enabled */
>> --
>>
>> _______________________________________________
>> Virtio-fs mailing list
>> Virtio-fs at redhat.com
>> https://www.redhat.com/mailman/listinfo/virtio-fs
> --
> Dr. David Alan Gilbert / dgilbert at redhat.com / Manchester, UK
> .
>
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