[LU-569] make lu_object cache size adjustable

• Type: Improvement
• Resolution: Won't Fix
• Priority: Minor
• Assignee: Jinshan Xiong (Inactive)
• Reporter: Jinshan Xiong (Inactive)

Description

lu_object cache is specified to consume 20% of total memory. This limits 200 clients can be mounted on one node. We should make it adjustable so that customers have a chance to configure it by their needs.

Issue Links

• is related to: LU-19 imperative recovery

Comments

[Build Master (Inactive)]

Integrated in lustre-master » i686,server,el5,inkernel #285
LU-569: Make lu_object cache size adjustable

Oleg Drokin : c8d7c99ec50c81a33eea43ed1c535fa4d65cef23
Files :

• lustre/obdclass/lu_object.c

[Build Master (Inactive)]

Integrated in lustre-master » x86_64,server,el5,inkernel #285
LU-569: Make lu_object cache size adjustable

Oleg Drokin : c8d7c99ec50c81a33eea43ed1c535fa4d65cef23
Files :

• lustre/obdclass/lu_object.c

[Build Master (Inactive)]

Integrated in lustre-master » x86_64,client,el6,inkernel #285
LU-569: Make lu_object cache size adjustable

Oleg Drokin : c8d7c99ec50c81a33eea43ed1c535fa4d65cef23
Files :

• lustre/obdclass/lu_object.c

[Build Master (Inactive)]

Integrated in lustre-master » x86_64,client,ubuntu1004,inkernel #285
LU-569: Make lu_object cache size adjustable

Oleg Drokin : c8d7c99ec50c81a33eea43ed1c535fa4d65cef23
Files :

• lustre/obdclass/lu_object.c

[Build Master (Inactive)]

Integrated in lustre-master » i686,client,el6,inkernel #285
LU-569: Make lu_object cache size adjustable

Oleg Drokin : c8d7c99ec50c81a33eea43ed1c535fa4d65cef23
Files :

• lustre/obdclass/lu_object.c

[Build Master (Inactive)]

Integrated in lustre-master » x86_64,server,el5,ofa #285
LU-569: Make lu_object cache size adjustable

Oleg Drokin : c8d7c99ec50c81a33eea43ed1c535fa4d65cef23
Files :

• lustre/obdclass/lu_object.c

[Build Master (Inactive)]

Integrated in lustre-master » i686,server,el6,inkernel #285
LU-569: Make lu_object cache size adjustable

Oleg Drokin : c8d7c99ec50c81a33eea43ed1c535fa4d65cef23
Files :

• lustre/obdclass/lu_object.c

[Build Master (Inactive)]

Integrated in lustre-master » x86_64,client,sles11,inkernel #285
LU-569: Make lu_object cache size adjustable

Oleg Drokin : c8d7c99ec50c81a33eea43ed1c535fa4d65cef23
Files :

• lustre/obdclass/lu_object.c

[Jinshan Xiong (Inactive)]

I'll use this patch for IR test only.

[Liang Zhen (Inactive)]

yes, they should be close, but it doesn't matter if they are handled by different threads on different CPUs, instead of "hog" one thread on one CPU for seconds.
we want to rehash(or grow hash-table) just because we don't want to allocate huge amount of big hash tables, for example, obd_class::exp_lock_hash, it is possible that there are tens of thousands of locks in this hash although most cases it shouldn't be that many, so we should allocate a small hash table on initializing of export and grow it only if necessary, as we can have over hundreds of thousands exports on server, it will save a lot of memory.

btw: although not fully tested, I remember the new cfs_hash can support "shrink" of hash-table which is non-blocking too, we probably should test and enable it in the future.

[Jinshan Xiong (Inactive)]

It will help, but if you are using an evenly distributed hash function, I could say the time for each first-level bucket to be rehashed will be really close.
I just don't understand the intention of rehashing feature, BTW.