Wall Street Firms Using CEP to Measure and Manage Risk
New complex event processing applications promise to help firms get a better handle on their risk exposure, but can CEP erase Wall Street's risk management woes.by Penny Crosman, Wallstreet & Technology.comOne of the many effects of the credit crisis is that Wall Street firms have found a new focus for their complex event processing projects. [...]
Hi
I have a system running solaris 10, and I intend to use a NetApp as its storage system. The application requires a throughput between the server and the storage 7000 disk IOPS (random IO sustained throughput with response time of 20 mili second and 16k block size).
How to make sure that I... (6 Replies)
BLK_MAKE_REQUEST(9) Block Devices BLK_MAKE_REQUEST(9)NAME
blk_make_request - given a bio, allocate a corresponding struct request.
SYNOPSIS
struct request * blk_make_request(struct request_queue * q, struct bio * bio, gfp_t gfp_mask);
ARGUMENTS
q
target request queue
bio
The bio describing the memory mappings that will be submitted for IO. It may be a chained-bio properly constructed by block/bio layer.
gfp_mask
gfp flags to be used for memory allocation
DESCRIPTION
blk_make_request is the parallel of generic_make_request for BLOCK_PC type commands. Where the struct request needs to be farther
initialized by the caller. It is passed a struct bio, which describes the memory info of the I/O transfer.
The caller of blk_make_request must make sure that bi_io_vec are set to describe the memory buffers. That bio_data_dir will return the
needed direction of the request. (And all bio's in the passed bio-chain are properly set accordingly)
If called under none-sleepable conditions, mapped bio buffers must not need bouncing, by calling the appropriate masked or flagged
allocator, suitable for the target device. Otherwise the call to blk_queue_bounce will BUG.
WARNING
When allocating/cloning a bio-chain, careful consideration should be given to how you allocate bios. In particular, you cannot use
__GFP_WAIT for anything but the first bio in the chain. Otherwise you risk waiting for IO completion of a bio that hasn't been submitted
yet, thus resulting in a deadlock. Alternatively bios should be allocated using bio_kmalloc instead of bio_alloc, as that avoids the
mempool deadlock. If possible a big IO should be split into smaller parts when allocation fails. Partial allocation should not be an error,
or you risk a live-lock.
COPYRIGHT Kernel Hackers Manual 2.6. July 2010 BLK_MAKE_REQUEST(9)