using smp to download/upload files from fs is extremely slow in compare to custom service

Question

hello Nordic 
 
 i am using nrf52832 +and nrf52840 with ncs v2.3.0 
 i am using little fs in the nrfs (which are the servers), i use SMP service for DFU. 
 when implementing smp service on my client and try to upload or download files to the servers i see it takes a very long time (~100kb /1min) 
 i wonder why it is so, what configuration might i miss ? 
 also when i add prints to every read of my external flash under the lfs, i see that it reads much more the 100kb, looks like it reads the same area over and over, so i wonder why does it behave like this and how can i fix it 
 another issue that is less related to smp and more to fs, it looks like file system asks the flash driver to read area that is not designated to fs in the .yml fils .. any ideas on that ? 
 hope to read from you soon 
 best regards 
 Ziv

ziv123 · Accepted Answer

figured it out myself eventually 
 so one of the reason for the slow transmission using the SMP service with file system is cause every event that generates a fs_mgmt_file_download/upload there is a file open operation which reads the data base in search for the file path. when working with external flash, which is much bigger then internal flash, it can take a lot of read operations. so solutions: 
 1. there is this config CONFIG_MCUMGR_BUF_SIZE (in ncs v.2.3.0, in v2.5.0 there is a different config for that) as large as we can make it the less events calling for open file operations we will have so larger buff will make transmission much faster. 
 2. in ncs v.2.5.0 there was a change that avoid the multiplication of fs_open operation, so fs_open is called once in the start of transmission and another time before the end (not sure yet why it is called the second time) which is much more efective 
 hope it helps someone, good luck all 
 best regards 
 Ziv

using smp to download/upload files from fs is extremely slow in compare to custom service

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