Messages in this thread Patch in this message | | | Date | Wed, 29 Oct 2008 14:18:55 +0100 | From | Jens Axboe <> | Subject | Re: [PATCH][v2] blktrace: conversion to tracepoints |
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On Wed, Oct 29 2008, Arnaldo Carvalho de Melo wrote: > Hi Jens, > > Now that the tracepoints infrastructure is merged I updated the > patch, please take a look. > > One suggestion I got was to have things like: > > trace_block_unplug_io(q, q->rq.count[READ] + q->rq.count[WRITE]); > > That was: > > blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL, > q->rq.count[READ] + q->rq.count[WRITE]); > > To be: > > trace_block_unplug_io(q, q->rq.count[READ], q->rq.count[WRITE]); > > Or even: > > trace_block_unplug_io(q); > > And on blk_add_trace_unplug_io tracepoint do the math and feed > it to __blk_add_trace. > > So that the information on the number of types of requests > instead of the sum, what do you think? Overengineering? For blktrace it > would end up being preserved as is in, say: > > static void blk_add_trace_unplug_io(struct request_queue *q, > unsigned int rd, unsigned int wr) > { > struct blk_trace *bt = q->blk_trace; > > if (bt) { > __be64 rpdu = cpu_to_be64(rd + wr); > > __blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_IO, 0, > sizeof(rpdu), &rpdu); > } > } > > Perhaps doing it as 'trace_block_unplug_io(q)' would be the best > scenario, as the tracepoint user can look at struct_request queue at > will anyway and the code gets cleaner :-) > > Feel free to point any disgusting aspect, perhaps there is at > least one to warn me about fixing 8-)
You my as well pass the members separately now that it's a specific call anyway, to avoid doing the calculation when tracing is disabled.
Patch looks straight forward. Perhaps it would be cleaner to use an atomic type for the reference?
> @@ -237,6 +243,10 @@ static void blk_trace_cleanup(struct blk_trace *bt) > free_percpu(bt->sequence); > free_percpu(bt->msg_data); > kfree(bt); > + mutex_lock(&blk_probe_mutex); > + if (--blk_probes_ref == 0) > + blk_unregister_tracepoints(); > + mutex_unlock(&blk_probe_mutex); > }
Then this would be
if (atomic_dec_and_test(&blk_probes_ref)) blk_unregister_tracepoints();
> int blk_trace_remove(struct request_queue *q) > @@ -428,6 +438,14 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev, > bt->pid = buts->pid; > bt->trace_state = Blktrace_setup; > > + mutex_lock(&blk_probe_mutex); > + if (!blk_probes_ref++) { > + ret = blk_register_tracepoints(); > + if (ret) > + goto probe_err; > + } > + mutex_unlock(&blk_probe_mutex); > +
And this would be
if (atomic_add_return(&blk_probes_ref, 1) == 1) { ret = blk_register_tracepoints(); if (ret) goto probe_err; }
-- Jens Axboe
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