2022-10-20 15:12 (UTC+0500), Huzaifa Rahman: > On Thu, Oct 6, 2022 at 3:42 PM Dmitry Kozlyuk <dmitry.kozl...@gmail.com> > wrote: > > > 2022-10-06 10:04 (UTC+0000), huzaifa.rahman: > > > Bugzilla ID: 560 > > > > > > The memory subsystem is leaving open a file descriptor for each > > > rtemap file. This can lead to hundreds of extra open file descriptors > > > which has negative side effects. For example, the application may go > > > over its maximum file descriptor limit, or the application may be using > > > limited API's like select that only allow 1024 file descriptors. > > > > > > The EAL memory subsystem does not need to hold the file open. > > > Probably the original intention was to keep the file locked, but that is > > > not necessary. The Linux kernel keeps a reference count on the file, > > > and the mmap counts is a reference and therefore maintains the file > > > as locked. > > > > > > The fix is just to close the file after it is setup. > > > > > > Signed-off-by: huzaifa.rahman <huzaifa.rah...@emumba.com> > > > --- > > > lib/eal/linux/eal_memalloc.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/lib/eal/linux/eal_memalloc.c b/lib/eal/linux/eal_memalloc.c > > > index f8b1588cae..955c4e4f95 100644 > > > --- a/lib/eal/linux/eal_memalloc.c > > > +++ b/lib/eal/linux/eal_memalloc.c > > > @@ -679,6 +679,9 @@ alloc_seg(struct rte_memseg *ms, void *addr, int > > socket_id, > > > > > > huge_recover_sigbus(); > > > > > > + close(fd); > > > + fd_list[list_idx].fds[seg_idx] = -1; > > > + > > > ms->addr = addr; > > > ms->hugepage_sz = alloc_sz; > > > ms->len = alloc_sz; > > > > This breaks rte_memseg_get_fd(). > > If memfd_create() was used to open the file descriptor, > > there seems no way to reopen it once closed. > > > > --single-file-segments may be used to save FD count, > > does using it solve your issue? > > > yes, It reduces the opened files from 450 to 2. > Is there any down side of using --single-file-segments flag. Because if > this is better why not make it the default behaviour.
Single-file segments option needs fallocate() kernel support to release pages to the kernel (see `resize_hugefile_in_filesystem` function). I wonder if DPDK still targets Linux/FreeBSD versions that lack this support. If not, I don't see an issue in changing the behavior and removing the option. Only it may be too late in this release and the change is a breaking one. Adding some people who might know more about DPDK usage. P.S. Moved the reply to the bottom to keep context.
