On Wed, Jun 29, 2022 at 5:23 AM Brian Foster <bfoster@xxxxxxxxxx> wrote: > > On Tue, Jun 28, 2022 at 03:38:02PM -0700, Kalesh Singh wrote: > > On Tue, Jun 28, 2022 at 4:54 AM Brian Foster <bfoster@xxxxxxxxxx> wrote: > > > > > > On Thu, Jun 23, 2022 at 03:06:06PM -0700, Kalesh Singh wrote: > > > > To be able to account the amount of memory a process is keeping pinned > > > > by open file descriptors add a 'size' field to fdinfo output. > > > > > > > > dmabufs fds already expose a 'size' field for this reason, remove this > > > > and make it a common field for all fds. This allows tracking of > > > > other types of memory (e.g. memfd and ashmem in Android). > > > > > > > > Signed-off-by: Kalesh Singh <kaleshsingh@xxxxxxxxxx> > > > > Reviewed-by: Christian König <christian.koenig@xxxxxxx> > > > > --- > > > > > > > > Changes in v2: > > > > - Add Christian's Reviewed-by > > > > > > > > Changes from rfc: > > > > - Split adding 'size' and 'path' into a separate patches, per Christian > > > > - Split fdinfo seq_printf into separate lines, per Christian > > > > - Fix indentation (use tabs) in documentaion, per Randy > > > > > > > > Documentation/filesystems/proc.rst | 12 ++++++++++-- > > > > drivers/dma-buf/dma-buf.c | 1 - > > > > fs/proc/fd.c | 9 +++++---- > > > > 3 files changed, 15 insertions(+), 7 deletions(-) > > > > > ... > > > > > > Also not sure if it matters that much for your use case, but something > > > worth noting at least with shmem is that one can do something like: > > > > > > # cat /proc/meminfo | grep Shmem: > > > Shmem: 764 kB > > > # xfs_io -fc "falloc -k 0 10m" ./file > > > # ls -alh file > > > -rw-------. 1 root root 0 Jun 28 07:22 file > > > # stat file > > > File: file > > > Size: 0 Blocks: 20480 IO Block: 4096 regular empty file > > > # cat /proc/meminfo | grep Shmem: > > > Shmem: 11004 kB > > > > > > ... where the resulting memory usage isn't reflected in i_size (but is > > > is in i_blocks/bytes). > > > > I tried a similar experiment a few times, but I don't see the same > > results. In my case, there is not any change in shmem. IIUC the > > fallocate is allocating the disk space not shared memory. > > > > Sorry, it was implied in my previous test was that I was running against > tmpfs. So regardless of fs, the fallocate keep_size semantics shown in > both cases is as expected: the underlying blocks are allocated and the > inode size is unchanged. > > What wasn't totally clear to me when I read this patch was 1. whether > tmpfs refers to Shmem and 2. whether tmpfs allowed this sort of > operation. The test above seems to confirm both, however, right? E.g., a > more detailed example: > > # mount | grep /tmp > tmpfs on /tmp type tmpfs (rw,nosuid,nodev,seclabel,nr_inodes=1048576,inode64) > # cat /proc/meminfo | grep Shmem: > Shmem: 5300 kB > # xfs_io -fc "falloc -k 0 1g" /tmp/file > # stat /tmp/file > File: /tmp/file > Size: 0 Blocks: 2097152 IO Block: 4096 regular empty file > Device: 22h/34d Inode: 45 Links: 1 > Access: (0600/-rw-------) Uid: ( 0/ root) Gid: ( 0/ root) > Context: unconfined_u:object_r:user_tmp_t:s0 > Access: 2022-06-29 08:04:01.301307154 -0400 > Modify: 2022-06-29 08:04:01.301307154 -0400 > Change: 2022-06-29 08:04:01.451312834 -0400 > Birth: 2022-06-29 08:04:01.301307154 -0400 > # cat /proc/meminfo | grep Shmem: > Shmem: 1053876 kB > # rm -f /tmp/file > # cat /proc/meminfo | grep Shmem: > Shmem: 5300 kB > > So clearly this impacts Shmem.. was your test run against tmpfs or some > other (disk based) fs? Hi Brian, Thanks for clarifying. My issue was tmpfs not mounted at /tmp in my system: ==> meminfo.start <== Shmem: 572 kB ==> meminfo.stop <== Shmem: 51688 kB > > FWIW, I don't have any objection to exposing inode size if it's commonly > useful information. My feedback was more just an fyi that i_size doesn't > necessarily reflect underlying space consumption (whether it's memory or > disk space) in more generic cases, because it sounds like that is really > what you're after here. The opposite example to the above would be > something like an 'xfs_io -fc "truncate 1t" /tmp/file', which shows a > 1TB inode size with zero additional shmem usage. >From these cases, it seems the more generic way to do this is by calculating the actual size consumed using the blocks. (i_blocks * 512). So in the latter example 'xfs_io -fc "truncate 1t" /tmp/file' the size consumed would be zero. Let me know if it sounds ok to you and I can repost the updated version. Thanks, Kalesh > > Brian > > > cat /proc/meminfo > meminfo.start > > xfs_io -fc "falloc -k 0 50m" ./xfs_file > > cat /proc/meminfo > meminfo.stop > > tail -n +1 meminfo.st* | grep -i '==\|Shmem:' > > > > ==> meminfo.start <== > > Shmem: 484 kB > > ==> meminfo.stop <== > > Shmem: 484 kB > > > > ls -lh xfs_file > > -rw------- 1 root root 0 Jun 28 15:12 xfs_file > > > > stat xfs_file > > File: xfs_file > > Size: 0 Blocks: 102400 IO Block: 4096 regular empty file > > > > Thanks, > > Kalesh > > > > > > > > Brian > > > > > > > > > > > /* show_fd_locks() never deferences files so a stale value is safe */ > > > > show_fd_locks(m, file, files); > > > > -- > > > > 2.37.0.rc0.161.g10f37bed90-goog > > > > > > > > > > > -- > To unsubscribe from this group and stop receiving emails from it, send an email to kernel-team+unsubscribe@xxxxxxxxxxx. >
