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1. Introduce module parameter perf_mode for only Aero/Sea generation HBAs.
2. Update IOC page1 fields according to performance mode.
Below are the performance modes that can be enabled with module parameter
perf_mode:
0: Balanced - Few high iops reply queues will be enabled. Interrupt
coalescing will be enabled only for these high iops reply descriptor
queues.
1: Iops - Interrupt coalescing will be enabled on all reply queues.
Coalescing timeout is set to 0x20.This is default value for Aero.
2: Latency - Interrupt coalescing will be enabled on all reply queues.
Coalescing timeout is set to 0xA. This is a legacy behavior similar to
Ventura & Invader HBA series.
Default perf mode set by driver will be balanced mode if the following
conditions are met:
- CPU vendor = Intel;
- Aero controller working in 16GT/s pcie speed
Performance mode will be set to latency mode for all other cases.
4k Random Read IO performance numbers on 24 SAS SSD drives for above three
permormance modes. Performance data is from Intel Skylake and HGST SS300
(drive model SDLL1DLR400GCCA1).
IOPs:
-----------------------------------------------------------------------
|perf_mode | qd = 1 | qd = 64 | note |
|-------------|--------|---------|-------------------------------------
|balanced | 259K | 3061k | Provides max performance numbers |
| | | | both on lower QD workload & |
| | | | also on higher QD workload |
|-------------|--------|---------|-------------------------------------
|iops | 220K | 3100k | Provides max performance numbers |
| | | | only on higher QD workload. |
|-------------|--------|---------|-------------------------------------
|latency | 246k | 2226k | Provides good performance numbers |
| | | | only on lower QD worklaod. |
-----------------------------------------------------------------------
Avarage Latency:
-----------------------------------------------------
|perf_mode | qd = 1 | qd = 64 |
|-------------|--------------|----------------------|
|balanced | 92.05 usec | 501.12 usec |
|-------------|--------------|----------------------|
|iops | 108.40 usec | 498.10 usec |
|-------------|--------------|----------------------|
|latency | 97.10 usec | 689.26 usec |
-----------------------------------------------------
Signed-off-by: Suganath Prabu S <suganath-prabu.subramani@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.