Hello Jianfeng,
On Thu, May 12, 2016 at 2:44 AM, Jianfeng Tan <jianfeng.tan at intel.com> wrote:
> This patch adds an option, --huge-trybest, to use a recover mechanism to
> the case that there are not so many hugepages (declared in sysfs), which
> can be used. It relys on a mem access to fault-in hugepages, and if fails
> with SIGBUS, recover to previously saved stack environment with
> siglongjmp().
>
> Besides, this solution fixes an issue when hugetlbfs is specified with an
> option of size. Currently DPDK does not respect the quota of a hugetblfs
> mount. It fails to init the EAL because it tries to map the number of free
> hugepages in the system rather than using the number specified in the quota
> for that mount.
>
> It's still an open issue with CONFIG_RTE_EAL_SINGLE_FILE_SEGMENTS. Under
> this case (such as IVSHMEM target), having hugetlbfs mounts with quota will
> fail to remap hugepages as it relies on having mapped all free hugepages
> in the system.
For such a case case, maybe having some warning log message when it
fails would help the user.
+ a known issue in the release notes ?
> diff --git a/lib/librte_eal/linuxapp/eal/eal_memory.c
> b/lib/librte_eal/linuxapp/eal/eal_memory.c
> index 5b9132c..8c77010 100644
> --- a/lib/librte_eal/linuxapp/eal/eal_memory.c
> +++ b/lib/librte_eal/linuxapp/eal/eal_memory.c
> @@ -417,12 +434,33 @@ map_all_hugepages(struct hugepage_file *hugepg_tbl,
> hugepg_tbl[i].final_va = virtaddr;
> }
>
> + if (orig && internal_config.huge_trybest) {
> + /* In linux, hugetlb limitations, like cgroup, are
> + * enforced at fault time instead of mmap(), even
> + * with the option of MAP_POPULATE. Kernel will send
> + * a SIGBUS signal. To avoid to be killed, save stack
> + * environment here, if SIGBUS happens, we can jump
> + * back here.
> + */
> + if (wrap_sigsetjmp()) {
> + RTE_LOG(DEBUG, EAL, "SIGBUS: Cannot mmap more
> "
> + "hugepages of size %u MB\n",
> + (unsigned)(hugepage_sz / 0x100000));
> + munmap(virtaddr, hugepage_sz);
> + close(fd);
> + unlink(hugepg_tbl[i].filepath);
> + return i;
> + }
> + *(int *)virtaddr = 0;
> + }
> +
> +
> /* set shared flock on the file. */
> if (flock(fd, LOCK_SH | LOCK_NB) == -1) {
> - RTE_LOG(ERR, EAL, "%s(): Locking file failed:%s \n",
> + RTE_LOG(DEBUG, EAL, "%s(): Locking file failed:%s \n",
> __func__, strerror(errno));
> close(fd);
> - return -1;
> + return i;
> }
>
> close(fd);
Maybe I missed something, but we are writing into some hugepage before
the flock has been called.
Are we sure there is nobody else using this hugepage ?
Especially, can't this cause trouble to a primary process running if
we start the exact same primary process ?
--
David Marchand
