Re: [PATCH] eal/linux: lower log level on allocation attempt failure

[Stephen Hemminger <stephen@networkplumber.org>]

On Wed, 26 Jun 2024 16:51:42 +0200
David Marchand <david.marchand@redhat.com> wrote:

> On a ARM system with only 2MB hugepages configured, EAL emits an error
> log with allocations larger than 512MB.
> 
> Example with testpmd:
> $ dpdk-testpmd --in-memory --no-pci --log-level=*:debug -- -i
> ...
> EAL: In-memory mode enabled, hugepages of size 33554432 bytes will be
> 	allocated anonymously
> EAL: No free 32768 kB hugepages reported on node 0
> EAL: In-memory mode enabled, hugepages of size 65536 bytes will be
> 	allocated anonymously
> EAL: No free 64 kB hugepages reported on node 0
> EAL: In-memory mode enabled, hugepages of size 1073741824 bytes will be
> 	allocated anonymously
> EAL: No free 1048576 kB hugepages reported on node 0
> ...
> EAL: Detected memory type: socket_id:0 hugepage_sz:1073741824
> EAL: Detected memory type: socket_id:0 hugepage_sz:33554432
> EAL: Detected memory type: socket_id:0 hugepage_sz:2097152
> EAL: Detected memory type: socket_id:0 hugepage_sz:65536
> EAL: Creating 2 segment lists: n_segs:32 socket_id:0
> 	hugepage_sz:1073741824
> ...
> EAL: Creating 2 segment lists: n_segs:1024 socket_id:0
> 	hugepage_sz:33554432
> ...
> EAL: Creating 4 segment lists: n_segs:8192 socket_id:0
> 	hugepage_sz:2097152
> ...
> EAL: Creating 4 segment lists: n_segs:8192 socket_id:0
> 	hugepage_sz:65536
> ...
> EAL: Trying to obtain current memory policy.
> EAL: Setting policy MPOL_PREFERRED for socket 0
> EAL: alloc_seg(): mmap() failed: Cannot allocate memory
> EAL: Ask a virtual area of 0x40000000 bytes
> EAL: Virtual area found at 0x140000000 (size = 0x40000000)
> EAL: attempted to allocate 2 segments, but only 0 were allocated
> EAL: Restoring previous memory policy: 4
> EAL: Trying to obtain current memory policy.
> EAL: Setting policy MPOL_PREFERRED for socket 0
> EAL: eal_memalloc_alloc_seg_bulk(): couldn't find suitable memseg_list
> EAL: Restoring previous memory policy: 4
> EAL: Trying to obtain current memory policy.
> EAL: Setting policy MPOL_PREFERRED for socket 0
> EAL: Restoring previous memory policy: 4
> EAL: request: mp_malloc_sync
> EAL: No shared files mode enabled, IPC is disabled
> EAL: Heap on socket 0 was expanded by 1064MB
> ...
> 
> The reason is that the memzone allocation (~1GB large) would require
> 17017 (32kB) segments. However, as displayed in the early logs, a 32kB
> memory segment list can only host 8192 segments (controlled by the build
> option RTE_MAX_MEMSEG_PER_LIST).
> 
> This log message is misleading as there is no issue in the end: the
> allocation succeeded with 2MB hugepages.
> 
> Fixes: 582bed1e1d1d ("mem: support mapping hugepages at runtime")
> Cc: stable@dpdk.org
> 
> Signed-off-by: David Marchand <david.marchand@redhat.com>
> ---

Acked-by: Stephen Hemminger <stephen@networkplumber.org>