On 11/18/2021 12:29 AM, Maurizio Lombardi wrote:

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On Thu, Nov 18, 2021 at 01:59:29AM +0000, Chaitanya Kulkarni wrote:

quoted

We will need blktests for this.

Also, can you share performance numbers with this patch and
the errors that you are getting without this patch ?

Ok, I will try to run blktests and provide some performance numbers.

Without this patch, writes get lost:

[root@kvm-02-guest03 ~]# nvme connect -t tcp -a 10.37.153.75 -n test-nqn -s 4080
[root@kvm-02-guest03 ~]# dd if=/dev/urandom of=/dev/nvme0n1 bs=1M count=1
1+0 records in
1+0 records out
1048576 bytes (1.0 MB, 1.0 MiB) copied, 0.0604551 s, 17.3 MB/s
[root@kvm-02-guest03 ~]# hexdump -C /dev/nvme0n1
00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
06400000

dmesg output:

[81489.687548] blk_update_request: critical target error, dev nvme0c0n1, sector 0 op 0x1:(WRITE) flags 0x2000800 phys_seg 256 prio class 0
[81489.691139] buffer_io_error: 246 callbacks suppressed
[81489.691141] Buffer I/O error on dev nvme0n1, logical block 0, lost async page write
[81489.695013] Buffer I/O error on dev nvme0n1, logical block 1, lost async page write
[81489.697183] Buffer I/O error on dev nvme0n1, logical block 2, lost async page write
[81489.699239] Buffer I/O error on dev nvme0n1, logical block 3, lost async page write
[81489.701297] Buffer I/O error on dev nvme0n1, logical block 4, lost async page write
[81489.703374] Buffer I/O error on dev nvme0n1, logical block 5, lost async page write
[81489.705459] Buffer I/O error on dev nvme0n1, logical block 6, lost async page write
[81489.707511] Buffer I/O error on dev nvme0n1, logical block 7, lost async page write
[81489.709438] Buffer I/O error on dev nvme0n1, logical block 8, lost async page write
[81489.711364] Buffer I/O error on dev nvme0n1, logical block 9, lost async page write

Maurizio

Thanks for the prompt reply and sharing this ..

Please send a formal-patch (non-RFC) with the testing done.