[dpdk-dev] [PATCH 14/41] eal: add support for mapping hugepages at runtime

[Olivier Matz]

On Sat, Mar 03, 2018 at 01:46:02PM +0000, Anatoly Burakov wrote:
> Nothing uses this code yet. The bulk of it is copied from old
> memory allocation code (linuxapp eal_memory.c). We provide an
> EAL-internal API to allocate either one page or multiple pages,
> guaranteeing that we'll get contiguous VA for all of the pages
> that we requested.
> 
> For single-file segments, we will use fallocate() to grow and
> shrink memory segments, however fallocate() is not supported
> on all kernel versions, so we will fall back to using
> ftruncate() to grow the file, and disable shrinking as there's
> little we can do there. This will enable vhost use cases where
> having single file segments is of great value even without
> support for hot-unplugging memory.
> 
> Not supported on FreeBSD.
> 
> Locking is done via fcntl() because that way, when it comes to
> taking out write locks or unlocking on deallocation, we don't
> have to keep original fd's around. Plus, using fcntl() gives us
> ability to lock parts of a file, which is useful for single-file
> segments.
> 
> Signed-off-by: Anatoly Burakov <anatoly.burakov at intel.com>

Few minor typos:

[...]

> +static void
> +resotre_numa(int *oldpolicy, struct bitmask *oldmask)

restore

[...]

> +static off_t
> +getFileSize(int fd)

should it be get_file_size()?

[...]

> +static int
> +alloc_page(struct rte_memseg *ms, void *addr, uint64_t size, int socket_id,
> +		struct hugepage_info *hi, unsigned int list_idx,
> +		unsigned int seg_idx)
> +{
> +	int cur_socket_id = 0;
> +	uint64_t map_offset;
> +	char path[PATH_MAX];
> +	int ret = 0;
> +	int fd;
> +
> +	fd = get_page_fd(path, sizeof(path), hi, list_idx, seg_idx);
> +	if (fd < 0)
> +		return -1;
> +
> +
> +	if (internal_config.single_file_segments) {
> +		map_offset = seg_idx * size;
> +		ret = resize_hugefile(fd, map_offset, size, true);
> +		if (ret < 1)
> +			goto resized;
> +	} else {
> +		map_offset = 0;
> +		if (ftruncate(fd, size) < 0) {
> +			RTE_LOG(DEBUG, EAL, "%s(): ftruncate() failed: %s\n",
> +				__func__, strerror(errno));
> +			goto resized;
> +		}
> +		/* we've allocated a page - take out a read lock. we're using
> +		 * fcntl() locks rather than flock() here because doing that
> +		 * gives us one huge advantage - fcntl() locks are per-process,
> +		 * not per-file descriptor, which means that we don't have to
> +		 * keep the original fd's around to keep a lock on the file.
> +		 *
> +		 * this is useful, because when it comes to unmapping pages, we
> +		 * will have to take out a write lock (to figure out if another
> +		 * process still has this page mapped), and to do itwith flock()

typo: itwith